You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
pytorch-image-models/timm/models/layers/cond_conv2d.py

122 lines
5.0 KiB

""" PyTorch Conditionally Parameterized Convolution (CondConv)
Paper: CondConv: Conditionally Parameterized Convolutions for Efficient Inference
(https://arxiv.org/abs/1904.04971)
Hacked together by Ross Wightman
"""
import math
from functools import partial
import numpy as np
import torch
from torch import nn as nn
from torch.nn import functional as F
from .helpers import tup_pair
from .conv2d_same import get_padding_value, conv2d_same
def get_condconv_initializer(initializer, num_experts, expert_shape):
def condconv_initializer(weight):
"""CondConv initializer function."""
num_params = np.prod(expert_shape)
if (len(weight.shape) != 2 or weight.shape[0] != num_experts or
weight.shape[1] != num_params):
raise (ValueError(
'CondConv variables must have shape [num_experts, num_params]'))
for i in range(num_experts):
initializer(weight[i].view(expert_shape))
return condconv_initializer
class CondConv2d(nn.Module):
""" Conditionally Parameterized Convolution
Inspired by: https://github.com/tensorflow/tpu/blob/master/models/official/efficientnet/condconv/condconv_layers.py
Grouped convolution hackery for parallel execution of the per-sample kernel filters inspired by this discussion:
https://github.com/pytorch/pytorch/issues/17983
"""
__constants__ = ['bias', 'in_channels', 'out_channels', 'dynamic_padding']
def __init__(self, in_channels, out_channels, kernel_size=3,
stride=1, padding='', dilation=1, groups=1, bias=False, num_experts=4):
super(CondConv2d, self).__init__()
self.in_channels = in_channels
self.out_channels = out_channels
self.kernel_size = tup_pair(kernel_size)
self.stride = tup_pair(stride)
padding_val, is_padding_dynamic = get_padding_value(
padding, kernel_size, stride=stride, dilation=dilation)
self.dynamic_padding = is_padding_dynamic # if in forward to work with torchscript
self.padding = tup_pair(padding_val)
self.dilation = tup_pair(dilation)
self.groups = groups
self.num_experts = num_experts
self.weight_shape = (self.out_channels, self.in_channels // self.groups) + self.kernel_size
weight_num_param = 1
for wd in self.weight_shape:
weight_num_param *= wd
self.weight = torch.nn.Parameter(torch.Tensor(self.num_experts, weight_num_param))
if bias:
self.bias_shape = (self.out_channels,)
self.bias = torch.nn.Parameter(torch.Tensor(self.num_experts, self.out_channels))
else:
self.register_parameter('bias', None)
self.reset_parameters()
def reset_parameters(self):
init_weight = get_condconv_initializer(
partial(nn.init.kaiming_uniform_, a=math.sqrt(5)), self.num_experts, self.weight_shape)
init_weight(self.weight)
if self.bias is not None:
fan_in = np.prod(self.weight_shape[1:])
bound = 1 / math.sqrt(fan_in)
init_bias = get_condconv_initializer(
partial(nn.init.uniform_, a=-bound, b=bound), self.num_experts, self.bias_shape)
init_bias(self.bias)
def forward(self, x, routing_weights):
B, C, H, W = x.shape
weight = torch.matmul(routing_weights, self.weight)
new_weight_shape = (B * self.out_channels, self.in_channels // self.groups) + self.kernel_size
weight = weight.view(new_weight_shape)
bias = None
if self.bias is not None:
bias = torch.matmul(routing_weights, self.bias)
bias = bias.view(B * self.out_channels)
# move batch elements with channels so each batch element can be efficiently convolved with separate kernel
x = x.view(1, B * C, H, W)
if self.dynamic_padding:
out = conv2d_same(
x, weight, bias, stride=self.stride, padding=self.padding,
dilation=self.dilation, groups=self.groups * B)
else:
out = F.conv2d(
x, weight, bias, stride=self.stride, padding=self.padding,
dilation=self.dilation, groups=self.groups * B)
out = out.permute([1, 0, 2, 3]).view(B, self.out_channels, out.shape[-2], out.shape[-1])
# Literal port (from TF definition)
# x = torch.split(x, 1, 0)
# weight = torch.split(weight, 1, 0)
# if self.bias is not None:
# bias = torch.matmul(routing_weights, self.bias)
# bias = torch.split(bias, 1, 0)
# else:
# bias = [None] * B
# out = []
# for xi, wi, bi in zip(x, weight, bias):
# wi = wi.view(*self.weight_shape)
# if bi is not None:
# bi = bi.view(*self.bias_shape)
# out.append(self.conv_fn(
# xi, wi, bi, stride=self.stride, padding=self.padding,
# dilation=self.dilation, groups=self.groups))
# out = torch.cat(out, 0)
return out