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问题：NameError：名称“ reduce”未在Python中定义
回答 0
回答 1
回答 2
回答 3

问题：NameError：名称“ reduce”未在Python中定义

我正在使用Python 3.2。试过这个：

xor = lambda x,y: (x+y)%2
l = reduce(xor, [1,2,3,4])

并得到以下错误：

l = reduce(xor, [1,2,3,4])
NameError: name 'reduce' is not defined

尝试打印reduce到交互式控制台中-出现此错误：

NameError: name 'reduce' is not defined


是reduce在Python 3.2中真正删除的吗？如果是这样，还有什么选择？

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I’m using Python 3.2. Tried this:

xor = lambda x,y: (x+y)%2
l = reduce(xor, [1,2,3,4])

And got the following error:

l = reduce(xor, [1,2,3,4])
NameError: name 'reduce' is not defined

Tried printing reduce into interactive console – got this error:

NameError: name 'reduce' is not defined


Is reduce really removed in Python 3.2? If that’s the case, what’s the alternative?

回答 0

它已移至functools。

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It was moved to functools.

回答 1

你可以加

from functools import reduce

在使用reduce之前。

点击查看英文原文

You can add

from functools import reduce

before you use the reduce.

回答 2

或者如果您使用六个库

from six.moves import reduce
点击查看英文原文

Or if you use the six library

from six.moves import reduce

回答 3

在这种情况下，我认为以下内容是等效的：

l = sum([1,2,3,4]) % 2

唯一的问题是它会产生大量数字，但这也许比重复的模运算更好？

点击查看英文原文

In this case I believe that the following is equivalent:

l = sum([1,2,3,4]) % 2

The only problem with this is that it creates big numbers, but maybe that is better than repeated modulo operations?

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