crscardellino crscardellino - 7 months ago 13
Python Question

Torch7 Tensor Non-Contiguos Index (Similar to Numpy)

I am new to torch7, and I can't find a way to get the some non contiguous indices of a tensor based on another tensor. In numpy, what I do is the following:

array = np.zeros(5) # array = [0 0 0 0 0]
indices = np.array([0, 2, 4])
array[indices] = np.array([1, 2, 3]) # array = [1 0 2 0 3]


Is there a way to do something similar in torch7? Something like:

array = torch.zeros(5) -- array = [0 0 0 0 0]
indices = torch.Tensor({1, 3, 5})
array[indices] = torch.Tensor({1, 2, 3}) -- array = [1 0 2 0 3]


Thanks!

Answer

Ok, looking arround, I couldn't find an exact solution, but I found an approximation of what I wanted to do, I share it in case someone else finds it useful:

array = torch.zeros(5) -- array = [0 0 0 0 0]
indices = torch.LongTensor({1, 3, 5}) -- Is important that this is a LongTensor
array:indexAdd(1, indices, torch.Tensor({1, 2, 3})) -- array = [1 0 2 0 3]
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