通過小於產生短名單蟒蛇運行列表

Question

a = [0,1,2,3,4,5,6] 
for x in a: 
    list(x < 4): 

預期輸出：[0,1,2,3] 實際輸出：[True, True, True, True, False, False, False]

任何想法如何得到我想要的東西？

Answer 1

a = [0,1,2,3,4,5,6] 
print ([x for x in a if x<4]) 

輸出;

[0, 1, 2, 3] 
>>> 

編輯後評論：它被稱爲list comprehension。

Answer 2

您可以使用filter：

>>> a = [0,1,2,3,4,5,6] 
>>> list(filter(lambda x: x < 4, a)) 
[0, 1, 2, 3] 

或itertools.takewhile（以防名單排序）：

>>> from itertools import takewhile 
>>> a = [0,1,2,3,4,5,6] 
>>> list(takewhile(lambda x: x < 4, a)) 
[0, 1, 2, 3]