int对象不是可迭代的python(int object is not iterable python)

int对象不是可迭代的python(int object is not iterable python) python

我正在尝试学习python reduce函数。

这是一些对我没有意义的代码

>>> x = [1,2,3] >>> reduce(sum, [b for b in x if b > 0]) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'int' object is not iterable >>> reduce(sum, [b for b in x if b > 2]) 3

当b> 2但b> 0时，为什么它可以工作？

代码看起来几乎完全相同

I am trying to learn python reduce function.

This is some code that does not make sense to me

>>> x = [1,2,3] >>> reduce(sum, [b for b in x if b > 0]) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'int' object is not iterable >>> reduce(sum, [b for b in x if b > 2]) 3

Why does it work when b > 2 but not b > 0

The code seems almost exactly the same

最满意答案

正如摩西所指出的那样“总和在第一次迭代中消耗了迭代”，所以让我们一起玩吧

>>> sum(1,2) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'int' object is not iterable >>> sum([1,2]) 3 >>> sum(x) 6 >>> sum([b for b in x if b >0]) 6 >>> reduce(lambda x, y: x+y, x) 6 >>> reduce(lambda x, y: x+y, [b for b in x if b > 0]) 6 >>> reduce(lambda x, y: x+y, [b for b in x if b > 1]) 5

As Moses points out "sum consumes the iterable in the first iteration" so let's play with it

>>> sum(1,2) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'int' object is not iterable >>> sum([1,2]) 3 >>> sum(x) 6 >>> sum([b for b in x if b >0]) 6 >>> reduce(lambda x, y: x+y, x) 6 >>> reduce(lambda x, y: x+y, [b for b in x if b > 0]) 6 >>> reduce(lambda x, y: x+y, [b for b in x if b > 1]) 5