1.查看reduce 的用法
在python 命令查看 import functools help(functools) help(functools.reduce) 或者 from functools import reduce help(reduce) Help on built-in function reduce in module _functools: reduce(...) reduce(function, sequence[, initial]) -> value Apply a function of two arguments cumulatively to the items of a sequence, from left to right, so as to reduce the sequence to a single value. For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates ((((1+2)+3)+4)+5). If initial is present, it is placed before the items of the sequence in the calculation, and serves as a default when the sequence is empty. >>> reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) 15 >>> reduce(lambda x, y: x*y, [1, 2, 3, 4, 5]) 120 >>>