是否可以在列表理解中使用"else"? [英] Is it possible to use 'else' in a list comprehension?

问题描述

这是我试图转变为列表理解的代码:

Here is the code I was trying to turn into a list comprehension:

table = ''
for index in xrange(256):
    if index in ords_to_keep:
        table += chr(index)
    else:
        table += replace_with

是否可以将else语句添加到此理解中?

Is there a way to add the else statement to this comprehension?

table = ''.join(chr(index) for index in xrange(15) if index in ords_to_keep)

推荐答案

语法a if b else c是Python中的三元运算符，如果条件b为true，则结果为a-否则，其结果为.可用于理解语句:

The syntax a if b else c is a ternary operator in Python that evaluates to a if the condition b is true - otherwise, it evaluates to c. It can be used in comprehension statements:

>>> [a if a else 2 for a in [0,1,0,3]]
[2, 1, 2, 3]

以您的示例为例，

table = ''.join(chr(index) if index in ords_to_keep else replace_with
                for index in xrange(15))

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