Indexing and Selection

PyTorch

Select tensor elements with slices, index arrays and masks. Distinguish views from copies and understand how indexing affects shape and shared storage.

9 exercises

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1 Not solved yet. Update selected rows, including repeated indices Practice · Medium
2 Not solved yet. Pick columns for each row Practice · Medium
3 Not solved yet. When two writes land on one slot Practice · Medium
4 Not solved yet. Zero the padding, keep the tensor Practice · Easy
5 Not solved yet. Mask the padding before the softmax Practice · Easy
6 Not solved yet. The value at the argmax Practice · Medium
7 Not solved yet. Rows 2 through 5, cheaply Practice · Easy
8 Not solved yet. Everything above the threshold Practice · Easy
9 Not solved yet. Labels to one-hot Practice · Medium

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0 / 4 correct

For this two-dimensional tensor, what do the two uses of -1 select?

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import torch

x = torch.arange(6).reshape(2, 3)
print(x[-1].tolist())
print(x.sum(dim=-1).tolist())

Question 1 of 4