当与if语句结合使用时，for循环忽略list的某些元素[duplicate]

This question already has an answer here:

这个问题在这里已有答案:

Loop “Forgets” to Remove Some Items [duplicate] 10 answers

循环“忘记”删除一些项目[重复] 10个答案

How to remove items from a list while iterating? 26 answers

迭代时如何从列表中删除项目? 26个答案

I would like to iterate over the elements of a list, and delete the wrong ones. First, lets check all elements:

我想迭代列表的元素,并删除错误的元素。首先,让我们检查所有元素:

tikzFiles=['keepme.tikz','inputs.tex','bla1.bat','bla2.tex','bla3.py']

for sFile in tikzFiles:
    print(sFile)
    print(sFile.endswith('.tikz'))

This leads to the expected result:

这导致了预期的结果:

keepme.tikz
True
inputs.tex
False
bla1.bat
False
bla2.tex
False
bla3.py
False

Two more lines, however,

还有两行,

for sFile in tikzFiles:
    print(sFile)
    print(sFile.endswith('.tikz'))
    if not sFile.endswith('.tikz'):
        tikzFiles.remove(sFile)

let the for-loop ignore the elements 'bla1.bat' and 'bla3.py':

让for-loop忽略元素'bla1.bat'和'bla3.py':

keepme.tikz
True
inputs.tex
False
bla2.tex
False

1 个解决方案

#1

Use list comprehension to create a new list with only the elements you want, like this

使用list comprehension创建一个只包含所需元素的新列表,如下所示

>>> tikzFiles = ['keepme.tikz', 'inputs.tex', 'bla1.bat', 'bla2.tex', 'bla3.py']
>>> [file for file in tikzFiles if file.endswith('.tikz')]
['keepme.tikz']

Note: More often, removing an element from a collection while you iterate it, is a bad idea. Check this answer to know more about what is actually going on at runtime.

注意:更常见的是,在迭代时从集合中删除元素是个坏主意。检查此答案以了解有关运行时实际运行情况的更多信息。

#1