什么是python中的％timeit？ [英] What is %timeit in python?

问题描述

我总是读取代码来计算这样的时间：

I always read the code to calculate the time like this way:

%timeit function()

你能在这里解释一下％的含义吗？

Can you explain what means "%" here?

我认为，％总是用于替换字符串中的某些内容，例如％s表示替换字符串，％d替换数据，但我没有关于这种情况的想法。

I think, the "%" is always used to replace something in a string, like %s means replace a string, %d replace a data, but I have no idea about this case.

推荐答案

％timeit 是 ipython magic 功能，可用于计时特定代码（单次执行）声明或单一方法）

%timeit is an ipython magic function, which can be used to time a particular piece of code (A single execution statement, or a single method)

来自文档：

％timeit

%timeit

Time execution of a Python statement or expression

Usage, in line mode:
    %timeit [-n<N> -r<R> [-t|-c] -q -p<P> -o] statement

要使用它，例如我们想要要确定使用 xrange 是否比使用范围更快，您可以这样做：

To use it, for example if we want to find out whether using xrange is any faster than using range, you can simply do:

In [1]: %timeit for _ in range(1000): True
10000 loops, best of 3: 37.8 µs per loop

In [2]: %timeit for _ in xrange(1000): True
10000 loops, best of 3: 29.6 µs per loop

你会得到他们的时间。

主要优点是你没有必须导入 timer.timeit ，并多次运行代码以确定哪种方法更好; ％timeit将根据总共2秒的执行窗口自动计算代码所需的运行次数。

The major advantage is that you don't have to import timer.timeit, and run the code multiple times to figure out which is the better approach; %timeit will automatically calculate number of runs required for your code based on a total of 2 seconds execution window.

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