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from typing import Sequence
from itertools import chain
import torch
import torch.nn as nn
from torchvision import models
from .utils import normalize_activation
def get_network(net_type: str):
if net_type == 'alex':
return AlexNet()
elif net_type == 'squeeze':
return SqueezeNet()
elif net_type == 'vgg':
return VGG16()
else:
raise NotImplementedError('choose net_type from [alex, squeeze, vgg].')
class LinLayers(nn.ModuleList):
def __init__(self, n_channels_list: Sequence[int]):
super(LinLayers, self).__init__([
nn.Sequential(
nn.Identity(),
nn.Conv2d(nc, 1, 1, 1, 0, bias=False)
) for nc in n_channels_list
])
for param in self.parameters():
param.requires_grad = False
class BaseNet(nn.Module):
def __init__(self):
super(BaseNet, self).__init__()
# register buffer
self.register_buffer(
'mean', torch.Tensor([-.030, -.088, -.188])[None, :, None, None])
self.register_buffer(
'std', torch.Tensor([.458, .448, .450])[None, :, None, None])
def set_requires_grad(self, state: bool):
for param in chain(self.parameters(), self.buffers()):
param.requires_grad = state
def z_score(self, x: torch.Tensor):
return (x - self.mean) / self.std
def forward(self, x: torch.Tensor):
x = self.z_score(x)
output = []
for i, (_, layer) in enumerate(self.layers._modules.items(), 1):
x = layer(x)
if i in self.target_layers:
output.append(normalize_activation(x))
if len(output) == len(self.target_layers):
break
return output
class SqueezeNet(BaseNet):
def __init__(self):
super(SqueezeNet, self).__init__()
self.layers = models.squeezenet1_1(True).features
self.target_layers = [2, 5, 8, 10, 11, 12, 13]
self.n_channels_list = [64, 128, 256, 384, 384, 512, 512]
self.set_requires_grad(False)
class AlexNet(BaseNet):
def __init__(self):
super(AlexNet, self).__init__()
self.layers = models.alexnet(True).features
self.target_layers = [2, 5, 8, 10, 12]
self.n_channels_list = [64, 192, 384, 256, 256]
self.set_requires_grad(False)
class VGG16(BaseNet):
def __init__(self):
super(VGG16, self).__init__()
self.layers = models.vgg16(weights=models.VGG16_Weights.IMAGENET1K_V1).features
self.target_layers = [4, 9, 16, 23, 30]
self.n_channels_list = [64, 128, 256, 512, 512]
self.set_requires_grad(False)