如果它的索引在另一個列表上，則從列表中獲取項目

Question

嗯，我在網站上看，我沒有找到任何可以幫助我的東西，所以我來問了。 如果它的索引在另一個列表中，我如何從列表中獲取項目？

例子：

我有一組向量：

[[0.0,0.0,0.1] [0.4,0.23,0.175] [0.0,1.,0.5] [0.0,0.03,0.1] [0.02,0.0,0.3]]

和索引列表：

[0,2,3]

我想要這樣的結果：

[[0.0,0.0,0.1] [0.0,1.,0.5] [0.0,0.03,0.1]]

我怎樣才能得到這個結果？ 感謝任何幫助:)

Answer 1

像這樣的東西

lst1 = [[0.0, 0.0, 0.1], [0.4, 0.23, 0.175], [0.0, 1., 0.5], [0.0, 0.03, 0.1], [0.02, 0.0, 0.3]]
lst2 = [0, 2, 3]
lst3 = [x for idx, x in enumerate(lst1) if idx in lst2]
print(lst3)

輸出

[[0.0, 0.0, 0.1], [0.0, 1.0, 0.5], [0.0, 0.03, 0.1]]

Answer 2

你可以通過列表理解來做到這一點。

例如：

mylist = [[0.0,0.0,0.1], [0.4,0.23,0.175], [0.0,1.,0.5], [0.0,0.03,0.1], [0.02,0.0,0.3]]
indices = [0,2,3]
result = [mylist[i] for i in indices]

結果現在是[[0.0, 0.0, 0.1], [0.0, 1.0, 0.5], [0.0, 0.03, 0.1]]