NameError: name 'reduce' is not defined in Python

问题

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1:

It was moved to functools.

回答2:

You can add

from functools import reduce

before you use the reduce.

回答3:

Or if you use the six library

from six.moves import reduce

回答4:

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?

来源：https://stackoverflow.com/questions/8689184/nameerror-name-reduce-is-not-defined-in-python