Question about dimension of y after applying mask in PixArt.py

[Starry-lei]

In the code: "if mask is not None:
if mask.shape[0] != y.shape[0]:
mask = mask.repeat(y.shape[0] // mask.shape[0], 1)
mask = mask.squeeze(1).squeeze(1)
y = y.squeeze(1).masked_select(mask.unsqueeze(-1) != 0).view(1, -1, x.shape[-1])
y_lens = mask.sum(dim=1).tolist()"

        why is  y viewed as (1, -1, x.shape[-1]) instead of (N, -1, x.shape[-1]) ?

[lawrence-cj]

later used in xformers