in models/swin_transformer_3d.py [0:0]
def forward(self, x, H=None, W=None):
"""Forward function.
Args:
x: Input feature, tensor size (B, D, H, W, C).
"""
if H is None:
B, D, H, W, C = x.shape
# padding
pad_input = (H % 2 == 1) or (W % 2 == 1)
if pad_input:
x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))
x0 = x[:, :, 0::2, 0::2, :] # B D H/2 W/2 C
x1 = x[:, :, 1::2, 0::2, :] # B D H/2 W/2 C
x2 = x[:, :, 0::2, 1::2, :] # B D H/2 W/2 C
x3 = x[:, :, 1::2, 1::2, :] # B D H/2 W/2 C
x = torch.cat([x0, x1, x2, x3], -1) # B D H/2 W/2 4*C
x = self.norm(x)
x = self.reduction(x)
return x