[英]Python removing elements from a 2d array depending on first item
If I were to have a 2d array in python, say 如果我在python中有一个2d数组,比如说
lst = [['a','1', '2'], ['b', 1, 2], ['c', 1, 2], ['b', 3, 4]]
I'd like a way to remove any items from lst where the first item is 'b', so that you return with: 我想要一种方法从第一项是'b'的lst中删除任何项目,以便您返回:
[['a','1', '2'], ['c', 1, 2]]
Any help would be greatly appreciated, preferred if only built in libraries are used. 如果只使用内置的库,则会非常感谢任何帮助。 Thanks 谢谢
Use a list comprehension 使用列表理解
lst = [['a','1', '2'], ['b', 1, 2], ['c', 1, 2], ['b', 3, 4]]
lst = [x for x in lst if x[0] != 'b']
print(lst)
prints 版画
[['a', '1', '2'], ['c', 1, 2]]
Not using an inbuilt library, but would probably be faster if the array is large, 不使用内置库,但如果数组很大,可能会更快,
import numpy as np
lst = np.array(lst)
a = lst[np.where(lst[:,0] != 'b')]
a.to_list()
[['a', '1', '2'], ['c', '1', '2']]
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