Python - 日期 &使用时间戳、timedelta 进行时间比较 [英] Python - Date & Time Comparison using timestamps, timedelta

问题描述

过去一个小时我一直在挖掘 Python 文档和许多 SO 问题；请原谅我是另一个被 Python 时差之谜困住的 Python 新手.

I've spent the past hour digging around the Python docs and many SO questions; please forgive me for being another Python newbie trapped by the mystery of time difference in Python.

我的目标是确定当前时间和某个日期/时间之间的差异，而不管是过去/未来，并返回一个可行的格式，例如秒.

例如，如果输入是 2:00PM 和 4:00PM(现在)，我希望它说-7200"，表示事件发生在两小时前.如果输入是周五下午 4:00(现在)和周日下午 5:00，则输出应该是176400"秒，代表从现在起两天零一小时.

For example, if the inputs are 2:00PM and 4:00PM (now), I'd like it to say "-7200", representing the event occurred two hours AGO. If the inputs are Fri 4:00PM (now) and Sun 5:00PM the output should be "176400" seconds, representing two days and 1 hour from now.

以下是我尝试过的东西...

Here are the things I've tried...

• 我的第一个版本是一个函数，它采用字符串时间戳并将其拼凑成多个变量，然后进行比较.它很笨重，有很多错误，我想如果我把它贴在这里，我会对程序员呕吐负责.

• My first version was a function that took a string timestamp and pieced it to multiple variables, and then compared them. It was clunky with many errors and I imagine if I posted it here I would be responsible for a programmers throwing up.

我偶然发现了这个神奇的 timedelta 函数，并研究了文档和 SO，但我认为它不能满足我的需求.

I stumbled upon this magical timedelta function and explored the docs and SO, but I don't think it does what I'm looking for.

我的想法是将两个时间戳转换为自纪元以来的秒数，然后减去，但是如果减去的顺序错误(如果事件发生在未来的情况不同)，这就会成为一个问题，我觉得就像添加 if 语句来检查秒的符号会很笨拙并且需要避免.

I had the idea to convert both timestamps into seconds since epoch and then subtract, but this becomes a problem if the subtraction is in the wrong order (different cases if the event is in the future), and I feel like adding if statements to check the sign of the seconds would be clunky and something to avoid.

这是我当前的代码(仍然需要修复以进行双向"比较)，来自以前解决的 SO 问题:

This is my current code (still needs to be fixed for 'bi-directional' comparison), from a previously resolved SO question:

now = time.strftime("%a %b %d %H:%M:%S %Y")
then = time.ctime(os.path.getmtime("x.cache"))
tdelta = datetime.strptime(now, '%a %b %d %H:%M:%S %Y') - datetime.strptime(then, '%a %b %d %H:%M:%S %Y')

而且我觉得我应该能够从中抽出几秒钟，就像在这个问题中一样:Python 的 timedelta:我不能在我想要的任何时间单位中获取整个差异的值吗?

And I feel like I should somehow be able to pull seconds from this, like in this question: Python's timedelta: can't I just get in whatever time unit I want the value of the entire difference?

但我不知道如何连接这些点.

But I am at a lost on how to connect these dots.

我怎样才能做到这一点?

How can I accomplish this?

推荐答案

你应该可以使用

tdelta.total_seconds()

获得您正在寻找的价值.这是因为 tdelta 是一个 timedelta 对象，以及 datetime 对象之间的任何差异.

to get the value you are looking for. This is because tdelta is a timedelta object, as is any difference between datetime objects.

一些注意事项:

1. 使用 strftime 后跟 strptime 是多余的.您应该能够使用 datetime.now.
2. 同样，使用 time.ctime 后跟 strptime 的工作量超出了需要.您应该能够使用 datetime 获取另一个 datetime 对象.fromtimestamp.

1. Using strftime followed by strptime is superfluous. You should be able to get the current datetime with datetime.now.
2. Similarly, using time.ctime followed by strptime is more work than needed. You should be able to get the other datetime object with datetime.fromtimestamp.

所以，你的最终代码可能是

So, your final code could be

now = datetime.now()
then = datetime.fromtimestamp(os.path.getmtime("x.cache"))
tdelta = now - then
seconds = tdelta.total_seconds()

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