递归删除列表元素 Python [英] Recursion removing list elements Python

问题描述

需要编写一个递归函数来删除列表中的元素但保留结果中的数组，例如.

need to write a recurive function to remove elements of list but keep the arrays in the result such as.

def remove_words(listx):
    for element in listx:
        if isinstance(element, list):
            remove_words(element)
        else:
            listx.remove(element)

    return listx

remove_words(["a", "b", ["c"]]) 将返回 [[]]

由于某种原因，我的代码返回 ["b",[]] 缺少一个元素.

My code returns ["b",[]] for some reason it's missing an element.

推荐答案

迭代时不要从集合中移除元素.重复调用 list.remove 在性能方面也不是理想的，因为每次删除(从随机索引)都是 O(N).解决这两个问题的一个简单方法是以下理解:

Do not remove elements from a collection while iterating it. Repeated calls to list.remove are also not ideal performance-wise since each removal (from a random index) is O(N). A simple way around both issues would be the following comprehension:

def remove_words(listx):
    return [remove_words(e) for e in listx if isinstance(e, list)]

看似缺失的基本情况是一个没有嵌套列表的列表，其中返回一个空列表.

The seemingly missing base case is a list with no nested lists where an empty list is returned.

如果要就地修改列表，可以使用切片赋值:

If you want to modify the list in-place, you can use slice assignment:

def remove_words(listx):
    listx[:] = [remove_words(e) for e in listx if isinstance(e, list)]

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