根据条件删除列表元素

Question

我有一份清单清单: [word, good freq, bad freq, change_status]

list_1 = [['good',100, 20, 0.2],['bad', 10, 0, 0.0],['change', 1, 2, 2]]

我想从列表中删除所有不满足条件的元素.

所以,如果change_status > 0.3 and bad_freq < 5那时我想删除与之对应的元素.

所以list_1会被修改为,

list_1 = [['good',100, 20, 0.2],['bad', 10, 0, 0.0]]

我如何选择性地做到这一点？

Answer 1

list_1 = [['good',100, 20, 0.2],['bad', 10, 0, 0.0],['change', 1, 2, 2]]
list_1 = [item for item in list_1 if item[2] >= 5 or item[3] >= 0.3]

if not (item[2] < 5 and item[3] < 0.3)如果需要,您也可以使用该条件.

Answer 2

使用filter具有适当功能的功能.

list_1 = filter(lambda x: x[3] <= 0.3 and x[2] < 5, list_1)

演示:

In [1]: list_1 = [['good',100, 20, 0.2],['bad', 10, 0, 0.0],['change', 1, 2, 2]]
In [2]: filter(lambda x: x[3] <= 0.3 and x[2] < 5, list_1)
Out[2]: [['bad', 10, 0, 0.0]]

请注意,即使你在问题中这么说,好也不能满足你的条件(20 < 5是假的)!

如果你有许多元素,你可能想要使用itertools中的等效函数:

from itertools import ifilter
filtered = ifilter(lambda x: x[3] <= 0.3 and x[2] < 5, list_1)