Python:为什么列表理解会产生一个生成器? [英] Python: why does list comprehension produce a generator?

问题描述

a=[['1','3','2'],['11','22','33']]
k = [(float(a[i][j]) for j in range(0,3)) for i in range(0,2)]
>>> print k
[<generator object <genexpr> at 0x7f1a9d568f50>, <generator object <genexpr> at 0x7f1a9d568fa0>]

但是我想得到[(1,3,2)，(11,22,33)] 为什么列表理解会产生一个生成器?

but I want to get [(1,3,2),(11,22,33)] why does list comprehension produce a generator?

推荐答案

您有一个生成器表达式[x for x in ...])中的>((x for x in ...)).这将返回生成器对象列表.像这样更改代码

You have a generator expression ((x for x in ...)) inside a list comprehension ([x for x in ...]). This will return a list of generator objects. Change the code like so

a = [['1','3','2'],['11','22','33']]
k = [[float(a[i][j]) for j in range(0,3)] for i in range(0,2)]

print(k)
# [[1.0, 3.0, 2.0], [11.0, 22.0, 33.0]]

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