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"""Miscellaneous neural network functionality."""
from typing import Tuple
from einops import rearrange
import torch
from torch.nn import Unfold
def sliding_window(
images: torch.Tensor, patch_size: Tuple[int, int], stride: Tuple[int, int]
) -> torch.Tensor:
"""Creates patches of an image.
Args:
images (torch.Tensor): A Torch tensor of a 4D image(s), i.e. (batch, channel, height, width).
patch_size (Tuple[int, int]): The size of the patches to generate, e.g. 28x28 for EMNIST.
stride (Tuple[int, int]): The stride of the sliding window.
Returns:
torch.Tensor: A tensor with the shape (batch, patches, height, width).
"""
unfold = Unfold(kernel_size=patch_size, stride=stride)
# Preform the slidning window, unsqueeze as the channel dimesion is lost.
patches = unfold(images).unsqueeze(1)
patches = rearrange(
patches, "b c (h w) t -> b t c h w", h=patch_size[0], w=patch_size[1]
)
return patches
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