就地替换python中列表中所有出现的元素 [英] In-place replacement of all occurrences of an element in a list in python

问题描述

假设我有一个列表:

myl = [1, 2, 3, 4, 5, 4, 4, 4, 6]

就地(双重强调)用替换所有4的最有效和最简单的pythonic方法是什么?>44?

What is the most efficient and simplest pythonic way of in-place (double emphasis) replacement of all occurrences of 4 with 44?

我也很好奇为什么没有 standard 这样做的方法(特别是当 strings 有一个 not-in-place replace 方法)?

I'm also curious as to why there isn't a standard way of doing this (especially, when strings have a not-in-place replace method)?

推荐答案

我们可以用 enumerate 遍历列表，并用新值替换旧值，就像这样

We can iterate over the list with enumerate and replace the old value with new value, like this

myl = [1, 2, 3, 4, 5, 4, 4, 4, 6]
for idx, item in enumerate(myl):
    if item == 4:
        myl[idx] = 44
print myl
# [1, 2, 3, 44, 5, 44, 44, 44, 6]

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