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pytorch-image-models/timm/models/layers/padding.py

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""" Padding Helpers
Hacked together by Ross Wightman
"""
import math
from typing import List
import torch.nn.functional as F
# Calculate symmetric padding for a convolution
def get_padding(kernel_size: int, stride: int = 1, dilation: int = 1, **_) -> int:
padding = ((stride - 1) + dilation * (kernel_size - 1)) // 2
return padding
# Calculate asymmetric TensorFlow-like 'SAME' padding for a convolution
def get_same_padding(x: int, k: int, s: int, d: int):
return max((math.ceil(x / s) - 1) * s + (k - 1) * d + 1 - x, 0)
# Can SAME padding for given args be done statically?
def is_static_pad(kernel_size: int, stride: int = 1, dilation: int = 1, **_):
return stride == 1 and (dilation * (kernel_size - 1)) % 2 == 0
# Dynamically pad input x with 'SAME' padding for conv with specified args
def pad_same(x, k: List[int], s: List[int], d: List[int] = (1, 1)):
ih, iw = x.size()[-2:]
pad_h, pad_w = get_same_padding(ih, k[0], s[0], d[0]), get_same_padding(iw, k[1], s[1], d[1])
if pad_h > 0 or pad_w > 0:
x = F.pad(x, [pad_w // 2, pad_w - pad_w // 2, pad_h // 2, pad_h - pad_h // 2])
return x