HI,
torch uses same convention as numpy such for finding values or indices of particular tensor regarding specific condition. torch.where 544 and torch.nonzero 339
What you can do is to apply your condition and get a binary mask of indices that match the condition and find the indices using torch.nonzero().
import torch

a = torch.randn(10)
b = a <= 0
indices = b.nonzero()

bests