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# Copyright (c) OpenMMLab. All rights reserved.
import logging
import torch.nn as nn
class AlexNet(nn.Module):
"""AlexNet backbone.
Args:
num_classes (int): number of classes for classification.
"""
def __init__(self, num_classes=-1):
super(AlexNet, self).__init__()
self.num_classes = num_classes
self.features = nn.Sequential(
nn.Conv2d(3, 64, kernel_size=11, stride=4, padding=2),
nn.ReLU(inplace=True),
nn.MaxPool2d(kernel_size=3, stride=2),
nn.Conv2d(64, 192, kernel_size=5, padding=2),
nn.ReLU(inplace=True),
nn.MaxPool2d(kernel_size=3, stride=2),
nn.Conv2d(192, 384, kernel_size=3, padding=1),
nn.ReLU(inplace=True),
nn.Conv2d(384, 256, kernel_size=3, padding=1),
nn.ReLU(inplace=True),
nn.Conv2d(256, 256, kernel_size=3, padding=1),
nn.ReLU(inplace=True),
nn.MaxPool2d(kernel_size=3, stride=2),
)
if self.num_classes > 0:
self.classifier = nn.Sequential(
nn.Dropout(),
nn.Linear(256 * 6 * 6, 4096),
nn.ReLU(inplace=True),
nn.Dropout(),
nn.Linear(4096, 4096),
nn.ReLU(inplace=True),
nn.Linear(4096, num_classes),
)
def init_weights(self, pretrained=None):
if isinstance(pretrained, str):
logger = logging.getLogger()
from ..runner import load_checkpoint
load_checkpoint(self, pretrained, strict=False, logger=logger)
elif pretrained is None:
# use default initializer
pass
else:
raise TypeError('pretrained must be a str or None')
def forward(self, x):
x = self.features(x)
if self.num_classes > 0:
x = x.view(x.size(0), 256 * 6 * 6)
x = self.classifier(x)
return x