[PyTorch] index_select, gather

index_select

>>> x = torch.randn(3, 4)
>>> x
tensor([[ 0.1427,  0.0231, -0.5414, -1.0009],
        [-0.4664,  0.2647, -0.1228, -1.1068],
        [-1.1734, -0.6571,  0.7230, -0.6004]])
>>> indices = torch.tensor([0, 2])
>>> torch.index_select(x, 0, indices)
tensor([[ 0.1427,  0.0231, -0.5414, -1.0009],
        [-1.1734, -0.6571,  0.7230, -0.6004]])
>>> torch.index_select(x, 1, indices)
tensor([[ 0.1427, -0.5414],
        [-0.4664, -0.1228],
        [-1.1734,  0.7230]])

 

tensor을 넣어야하지만 꼭 범위여야 하는건 아니다.(스칼라 값도 가능)

축에 관해서는

0 = 가로

1 = 세로

그 이상은 직접!

 

gather

 

 

https://runebook.dev/ko/docs/pytorch/generated/torch.index_select

https://pytorch.org/docs/stable/generated/torch.index_select.html?highlight=index#torch.index_select