<p><a >python</a>处理日期时间数据的核心在于使用datetime模块。1.datetime模块提供了date、time、datetime、timedelta和tzinfo等关键类，用于创建、操作和格式化日期时间。2.可通过datetime.now()获取当前日期时间，或通过指定参数构建特定日期时间对象。3.使用strftime方法按格式代码将datetime对象格式化为字符串，如%y-%m-%d %h:%m:%s。4.使用strptime方法将<a >字符串解析</a>为datetime对象，但格式字符串必须严格匹配输入。5.timedelta用于表示时间差，支持日期时间的加减运算，如计算未来或过去的时间点。6.处理时区时推荐使用pytz库，它提供了完整的时区支持，包括夏令时自动调整。7.datetime对象可直接比较和排序，内部基于时间点进行判断。8.常见陷阱包括混淆天真与感知日期时间、strptime格式不匹配以及夏令时处理问题。9.性能优化包括避免不必要的datetime对象创建、使用time.time()获取时间戳，以及在批量处理时使用pandas等高效库。</p> <p><img src=”https://img.php.cn/upload/article/001/503/042/175409401051011.png” alt=”Python如何处理日期时间数据？datetime全攻略”></p> <p>Python处理日期时间数据，核心在于使用其内置的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>模块。这个模块提供了一套全面的类和方法，能够让我们轻松地创建、操作、格式化以及解析日期和时间信息，是进行时间相关计算和展示的基础。</p> <img src=”https://img.php.cn/upload/article/001/503/042/175409401050659.png” alt=”Python如何处理日期时间数据？datetime全攻略”><h3>解决方案</h3> <p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>模块是Python处理日期时间数据的瑞士军刀。它主要提供了以下几个关键类：<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>date</pre><div class=”contentsignin”></div></div>（日期）、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>time</pre><div class=”contentsignin”></div></div>（时间）、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>（日期和时间）、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>timedelta</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>（时间差）以及<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>tzinfo</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>（时区信息）。理解这些类的作用，就能掌握大部分日期时间操作。</p> <p><strong>创建日期时间对象</strong></p> <p><span>立即学习</span>“<a href=”https://pan.quark.cn/s/00968c3c2c15″ style=”text-decoration: underline !important; color: blue; font-weight: bolder;” rel=”nofollow” target=”_blank”>Python免费学习笔记（深入）</a>”；</p> <img src=”https://img.php.cn/upload/article/001/503/042/175409401051011.png” alt=”Python如何处理日期时间数据？datetime全攻略”><p>最常见的，我们可能需要获取当前日期时间，或者根据特定值构建一个。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>from datetime import date, time, datetime, timedelta, timezone # 获取当前日期时间 now = datetime.now() print(f"当前日期时间: {now}") # 包含微秒 # 获取今天的日期 today = date.today() print(f"今天的日期: {today}") # 构建特定日期时间 # 2023年10月26日 下午3点30分0秒 specific_dt = datetime(2023, 10, 26, 15, 30, 0) print(f"特定日期时间: {specific_dt}") # 构建特定日期 specific_date = date(2024, 1, 1) print(f"特定日期: {specific_date}") # 构建特定时间 specific_time = time(9, 15, 45) print(f"特定时间: {specific_time}")</pre><div class=”contentsignin”></div></div><p><strong>访问日期时间组件</strong></p> <img src=”https://img.php.cn/upload/article/001/503/042/175409401139177.png” alt=”Python如何处理日期时间数据？datetime全攻略”><p>创建了<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象后，你可以很方便地访问它的各个部分，比如年、月、日、小时等等。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>dt = datetime(2023, 10, 26, 15, 30, 0, 123456) print(f"年份: {dt.year}") print(f"月份: {dt.month}") print(f"日期: {dt.day}") print(f"小时: {dt.hour}") print(f"分钟: {dt.minute}") print(f"秒数: {dt.second}") print(f"微秒: {dt.microsecond}") print(f"星期几 (0=周一, 6=周日): {dt.weekday()}") print(f"ISO 星期几 (1=周一, 7=周日): {dt.isoweekday()}")</pre><div class=”contentsignin”></div></div><p><strong>格式化日期时间 (<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strftime</pre><div class=”contentsignin”></div></div>)</strong></p> <p>将<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象转换为人类可读的字符串，是日常开发中很常见的需求。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strftime()</pre><div class=”contentsignin”></div></div>方法就是为此而生，它使用各种格式代码来控制输出。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>dt = datetime.now() # 常用格式 print(f"标准日期时间: {dt.strftime(‘%Y-%m-%d %H:%M:%S’)}") print(f"中文日期时间: {dt.strftime(‘%Y年%m月%d日 %H时%M分%S秒’)}") print(f"只显示日期: {dt.strftime(‘%x’)}") # 等同于 %m/%d/%y 或 %d/%m/%y 取决于系统 locale print(f"只显示时间: {dt.strftime(‘%X’)}") # 等同于 %H:%M:%S 或 %I:%M:%S %p 取决于系统 locale print(f"星期几全称: {dt.strftime(‘%A’)}") # 例如 ‘Thursday’ print(f"一年中的第几天: {dt.strftime(‘今天是今年的第%j天’)}")</pre><div class=”contentsignin”></div></div><p>我个人觉得，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>%Y-%m-%d %H:%M:%S</pre><div class=”contentsignin”></div></div>这个格式是万金油，用起来最顺手，也最不容易出错。</p> <p><strong>解析日期时间字符串 (<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strptime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>)</strong></p> <p>反过来，将一个日期时间字符串解析成<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象，就得用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strptime()</pre><div class=”contentsignin”></div></div>了。这里有个坑，就是你提供的格式字符串必须和输入字符串完全匹配，差一点都不行，不然就报错。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>date_str1 = "2023-10-26 15:30:00" dt1 = datetime.strptime(date_str1, "%Y-%m-%d %H:%M:%S") print(f"解析字符串1: {dt1}") date_str2 = "Oct 26, 2023 3:30 PM" # 注意这里的小时是12小时制，需要用 %I 和 %p dt2 = datetime.strptime(date_str2, "%b %d, %Y %I:%M %p") print(f"解析字符串2: {dt2}") # 错误示例：格式不匹配会抛出 ValueError try: datetime.strptime("2023/10/26", "%Y-%m-%d") except ValueError as e: print(f"解析错误: {e}")</pre><div class=”contentsignin”></div></div><p><strong>时间差计算 (<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>timedelta</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>)</strong></p> <p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>timedelta</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象代表两个日期或时间之间的差值，或者说是一段时间。它在计算未来或过去的日期时间，以及测量事件持续时间时非常有用。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’># 创建一个时间差 one_day = timedelta(days=1) one_hour = timedelta(hours=1) ten_minutes = timedelta(minutes=10) dt_now = datetime.now() print(f"当前时间: {dt_now}") # 未来一天 dt_tomorrow = dt_now + one_day print(f"明天: {dt_tomorrow}") # 过去两小时 dt_two_hours_ago = dt_now – timedelta(hours=2) print(f"两小时前: {dt_two_hours_ago}") # 计算两个日期时间之间的差值 dt_past = datetime(2023, 10, 1, 10, 0, 0) time_diff = dt_now – dt_past print(f"时间差: {time_diff}") print(f"时间差的总秒数: {time_diff.total_seconds()}") print(f"时间差的天数: {time_diff.days}")</pre><div class=”contentsignin”></div></div><p>用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>timedelta</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>做加减法，那种感觉就像在时间轴上跳跃，特别直观。</p> <h3>Python中处理时区问题的最佳实践是什么？</h3> <p>处理时区问题，尤其是涉及到跨地域或夏令时（DST）的场景，是日期时间操作里一个不小的挑战。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>模块自带<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>tzinfo</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>，但通常我们更倾向于使用第三方库<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>。<a >为什么</a>呢？因为<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>提供了全球时区数据库（IANA Time Zone database），能很好地处理各种复杂的时区规则，包括夏令时的自动调整。</p> <p>说白了，Python内置的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>tzinfo</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>接口是有的，但要自己实现所有的时区规则，那工作量可就大了去了。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>就是把这活儿给干了。</p> <p><strong>核心概念：天真（N<a >ai</a>ve）与感知（Aware）日期时间</strong></p> <p>在深入之前，得先搞清楚两个概念：</p> <ul> <li> <strong>天真（Naive）日期时间：</strong> 不包含任何时区信息的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象。比如 <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime(2023, 10, 26, 15, 30)</pre><div class=”contentsignin”></div></div>。它不知道自己是哪个时区的下午3点半。</li> <li> <strong>感知（Aware）日期时间：</strong> 包含了明确时区信息的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象。例如，知道自己是“北京时间下午3点半”或者“UTC时间下午3点半”。</li> </ul> <p>天真日期时间在只涉及本地时间且不跨时区计算时没问题，但一旦需要跨时区转换或考虑夏令时，就必须使用感知日期时间。</p> <p><strong>使用 <div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div> 处理时区</strong></p> <p>首先，你需要安装<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>：<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pip install pytz</pre><div class=”contentsignin”></div></div>。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>import pytz from datetime import datetime # 1. 获取一个时区对象 tz_utc = pytz.utc tz_london = pytz.timezone(‘Europe/London’) tz_shanghai = pytz.timezone(‘Asia/Shanghai’) # 2. 创建一个带时区的datetime对象 # 推荐做法：先创建UTC时间，再转换为目标时区 dt_utc_now = datetime.now(tz_utc) print(f"UTC 当前时间: {dt_utc_now}") # 或者，创建一个天真datetime，然后localize到特定时区 # 注意：localize只应在你知道这个天真datetime实际属于哪个时区时使用 dt_naive = datetime(2023, 10, 26, 15, 30, 0) dt_shanghai_aware = tz_shanghai.localize(dt_naive) print(f"上海时间（由天真转感知）: {dt_shanghai_aware}") # 3. 时区转换 (astimezone) dt_london_from_shanghai = dt_shanghai_aware.astimezone(tz_london) print(f"从上海时间转换到伦敦时间: {dt_london_from_shanghai}") # 从UTC转换到上海时间 dt_shanghai_from_utc = dt_utc_now.astimezone(tz_shanghai) print(f"从UTC转换到上海时间: {dt_shanghai_from_utc}") # 4. 处理夏令时边界（pytz的优势） # 假设我们想看某个夏令时切换点 # 伦敦在2023年10月29日凌晨2点（夏令时）变为凌晨1点（标准时） dt_before_dst = tz_london.localize(datetime(2023, 10, 29, 1, 30, 0)) # 凌晨1:30 BST dt_after_dst = tz_london.localize(datetime(2023, 10, 29, 2, 30, 0)) # 凌晨2:30 GMT (实际是1:30 BST+1hr) print(f"伦敦夏令时前: {dt_before_dst}") print(f"伦敦夏令时后: {dt_after_dst}") # 这里的localize会自动处理重复或缺失的时间点，这是pytz的强大之处</pre><div class=”contentsignin”></div></div><p>我发现，在处理时区时，最好的习惯是所有内部存储和计算都基于UTC时间。只有在展示给用户或者从外部系统接收数据时，才进行时区转换。这能极大程度地避免各种“时间跳跃”或“时间重复”的怪问题。</p> <h3>如何在Python中高效地比较和排序日期时间数据？</h3> <p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象可以直接进行比较和排序，这得益于它们内部实现了比较运算符。效率方面，在大多数应用场景下，直接比较<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象就已经足够高效了。</p> <p><strong>比较日期时间</strong></p> <p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象可以直接使用标准的比较运算符（<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>></pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><=</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>>=</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>==</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>!=</pre><div class=”contentsignin”></div></div>）。比较的逻辑是基于它们所代表的时间点，越早的时间点越“小”。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>from datetime import datetime dt1 = datetime(2023, 10, 26, 10, 0, 0) dt2 = datetime(2023, 10, 26, 11, 0, 0) dt3 = datetime(2023, 10, 26, 10, 0, 0) print(f”dt1 < dt2: {dt1 < dt2}”) # True print(f”dt1 == dt3: {dt1 == dt3}”) # True print(f”dt2 >= dt1: {dt2 >= dt1}”) # True # 注意：不同时区的感知datetime对象比较时，会先转换为共同的UTC时间再比较 from pytz import utc, timezone dt_utc = datetime(2023, 10, 26, 10, 0, 0, tzinfo=utc) dt_shanghai = datetime(2023, 10, 26, 18, 0, 0, tzinfo=timezone(‘Asia/Shanghai’)) # 也是UTC 10:00:00 print(f”dt_utc == dt_shanghai: {dt_utc == dt_shanghai}”) # True，因为它们代表同一UTC时间点</pre><div class=”contentsignin”></div></div><p>这一点很重要，特别是带有时区信息的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象，它们的比较是“智能”的，会考虑时区差异。</p> <p><strong>排序日期时间数据</strong></p> <p>对包含<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象的列表进行排序，和排序普通数字或字符串一样简单。Python的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>sort()</pre><div class=”contentsignin”></div></div>方法和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>sorted()</pre><div class=”contentsignin”></div></div>函数都能直接处理。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>from datetime import datetime dt_list = [ datetime(2023, 10, 26, 15, 0, 0), datetime(2023, 10, 25, 10, 0, 0), datetime(2023, 10, 26, 9, 0, 0), datetime(2023, 10, 27, 18, 0, 0) ] print(f"原始列表: {dt_list}") # 列表原地排序 dt_list.sort() print(f"排序后列表: {dt_list}") # 使用 sorted() 函数返回新列表 another_dt_list = [ datetime(2023, 1, 1), datetime(2022, 12, 31), datetime(2023, 1, 2) ] sorted_another_dt_list = sorted(another_dt_list) print(f"sorted() 函数排序后: {sorted_another_dt_list}") # 对包含datetime对象的复杂数据结构进行排序 class Event: def __init__(self, name, start_time): self.name = name self.start_time = start_time def __repr__(self): return f"Event(‘{self.name}’, {self.start_time.strftime(‘%Y-%m-%d %H:%M’)})" events = [ Event("Meeting A", datetime(2023, 10, 26, 10, 0)), Event("Lunch", datetime(2023, 10, 26, 12, 30)), Event("Project Review", datetime(2023, 10, 25, 16, 0)), Event("Daily Standup", datetime(2023, 10, 26, 9, 30)) ] # 按开始时间排序事件 events.sort(key=lambda event: event.start_time) print(f"按开始时间排序的事件: {events}")</pre><div class=”contentsignin”></div></div><p>对于性能，除非你是在处理百万级别甚至更高量级的日期时间数据，否则直接使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象进行比较和排序，其性能开销通常不是瓶颈。Python的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象在底层是相当优化的。如果真的遇到性能问题，可以考虑将日期时间转换为unix时间戳（一个整数），因为整数的比较和排序速度会更快，但这会牺牲一点代码的可读性。我一般不会这么做，除非分析器告诉我这里是瓶颈。</p> <h3>处理日期时间数据时，有哪些常见的陷阱和性能优化点？</h3> <p>在日期时间处理的旅程中，总有些意想不到的“坑”等着我们，同时也有一些小技巧能让代码跑得更快、更稳健。</p> <p><strong>常见的陷阱</strong></p> <ol> <li> <p><strong>天真（Naive）与感知（Aware）日期时间混淆：</strong> 这是最常见的，也是最隐蔽的陷阱。如果你在处理日期时间时不带时区信息（即使用天真<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>），那么在进行跨时区转换或夏令时计算时，结果几乎肯定会错。比如，你把一个天真的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象从服务器A（UTC时区）传到服务器B（东八区），然后直接用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime.now()</pre><div class=”contentsignin”></div></div>比较，那就会出问题。</p> <ul><li> <strong>解决方案：</strong> 始终使用感知<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象进行关键的时间点记录和计算。用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>给<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象打上时区标签。</li></ul> </li> <li> <p><strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strptime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>格式字符串不匹配：</strong> 前面提到过，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strptime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对格式要求非常严格。字符串中的任何额外字符、空格，或者格式代码的顺序不符，都会导致<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>ValueError</pre><div class=”contentsignin”></div></div>。</p> <ul><li> <strong>解决方案：</strong> 仔细核对输入字符串和格式代码。对于不确定或多变的输入格式，可能需要尝试多种格式，或者使用更灵活的解析库（如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>dateutil.parser.parse</pre><div class=”contentsignin”></div></div>，它能自动识别多种日期时间格式，但性能略低）。</li></ul> </li> <li> <p><strong>夏令时（DST）的“跳跃”和“重复”：</strong> 在夏令时切换的日子里，时间可能会向前跳一小时（春天），或者向后重复一小时（秋天）。如果你直接用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>timedelta</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>在这些边界上加减，可能会得到非预期的结果。例如，在夏令时结束那天，凌晨2点可能出现两次。</p> <ul><li> <strong>解决方案：</strong> <div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>在处理夏令时方面做得很好。当你使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz.timezone.localize()</pre><div class=”contentsignin”></div></div>或<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>astimezone()</pre><div class=”contentsignin”></div></div>时，它会根据IANA时区数据库的规则自动处理这些特殊情况。所以，尽量依赖<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pytz</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>来处理时区相关的加减法和转换。</li></ul> </li> <li><p><strong>闰年和闰秒：</strong> <div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>模块对闰年（如2月29日）的处理是正确的。但闰秒（在特定年份的6月30日或12月31日增加一秒）是另一个层面的复杂性，Python的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>模块通常不直接处理闰秒。对于绝大多数应用，这都不是问题，因为闰秒非常罕见且影响微乎其微。但如果你在做高精度的时间同步或物理测量，可能需要更专业的NTP（网络时间协议）服务。</p></li> </ol> <p><strong>性能优化点</strong></p> <ol> <li> <p><strong>避免不必要的对象创建：</strong> 如果你仅仅需要一个时间戳（例如，用于日志记录或文件命名），直接使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>time.time()</pre><div class=”contentsignin”></div></div>获取Unix时间戳（浮点数）会比创建<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>datetime</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象再转换为时间戳更快。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:python;toolbar:false;’>import time # 比 datetime.now().timestamp() 稍快 current_unix_timestamp = time.time()</pre><div class=”contentsignin”></div></div></li> <li><p><strong>批量解析和格式化：</strong> 对于大量日期时间字符串的解析或格式化，如果性能成为瓶颈，可以考虑使用专门为数据分析设计的库，如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pandas</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pandas</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>to_datetime</pre><div class=”contentsignin”></div></div>函数底层使用c语言优化，处理大量日期时间</p></li> </ol>
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