为什么减少函数询问参数

Question

我已经用reduce内置函数编写了这些代码行，但它显示了给定参数的错误。

45 lst=[1,2,3]中的TypeError回溯（最近一次调用）----

TypeError:d_n（）接受1个位置参数，但给出了2个

from functools import reduce
def d_n(digit):
    return(digit)

lst = [1,2,3]
reduce(d_n, lst)

Answer 1

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.

关键点：两个参数的函数

您的d_n（）函数只接受一个参数，这使得它与reduce