I am trying to use torch.unique() 3.
Let’s say I have a 2D tensor X = [[1, 2, 3, 4], [1, 2, 3, 4], [3, 4, 5, 6]]. If I use the operation output, inverse_indices = torch.unique(X), sorted=True, return_inverse=True, dim=0), then output would be   [[1, 2, 3, 4], [3, 4, 5, 6]]  and inverse_indices would be [0, 0, 1].
That is, inverse_indices is a tensor of the same length as X and tells us the index of elements of X with respect to the tensor output.
Is there a way to obtain the “reverse” of inverse indices? That is, I want to obtain the indices of output with respect to X. For example, in this case, I want to obtain the indices as [0, 2] (or [1, 2]). I understand that this “reverse” inverse index is not unique since multiple elements of X can be mapped to the same element in output.