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mmdet.models.backbones.resnext 源代码

# Copyright (c) OpenMMLab. All rights reserved.
import math

from mmcv.cnn import build_conv_layer, build_norm_layer

from ..builder import BACKBONES
from ..utils import ResLayer
from .resnet import Bottleneck as _Bottleneck
from .resnet import ResNet


class Bottleneck(_Bottleneck):
    expansion = 4

    def __init__(self,
                 inplanes,
                 planes,
                 groups=1,
                 base_width=4,
                 base_channels=64,
                 **kwargs):
        """Bottleneck block for ResNeXt.

        If style is "pytorch", the stride-two layer is the 3x3 conv layer, if
        it is "caffe", the stride-two layer is the first 1x1 conv layer.
        """
        super(Bottleneck, self).__init__(inplanes, planes, **kwargs)

        if groups == 1:
            width = self.planes
        else:
            width = math.floor(self.planes *
                               (base_width / base_channels)) * groups

        self.norm1_name, norm1 = build_norm_layer(
            self.norm_cfg, width, postfix=1)
        self.norm2_name, norm2 = build_norm_layer(
            self.norm_cfg, width, postfix=2)
        self.norm3_name, norm3 = build_norm_layer(
            self.norm_cfg, self.planes * self.expansion, postfix=3)

        self.conv1 = build_conv_layer(
            self.conv_cfg,
            self.inplanes,
            width,
            kernel_size=1,
            stride=self.conv1_stride,
            bias=False)
        self.add_module(self.norm1_name, norm1)
        fallback_on_stride = False
        self.with_modulated_dcn = False
        if self.with_dcn:
            fallback_on_stride = self.dcn.pop('fallback_on_stride', False)
        if not self.with_dcn or fallback_on_stride:
            self.conv2 = build_conv_layer(
                self.conv_cfg,
                width,
                width,
                kernel_size=3,
                stride=self.conv2_stride,
                padding=self.dilation,
                dilation=self.dilation,
                groups=groups,
                bias=False)
        else:
            assert self.conv_cfg is None, 'conv_cfg must be None for DCN'
            self.conv2 = build_conv_layer(
                self.dcn,
                width,
                width,
                kernel_size=3,
                stride=self.conv2_stride,
                padding=self.dilation,
                dilation=self.dilation,
                groups=groups,
                bias=False)

        self.add_module(self.norm2_name, norm2)
        self.conv3 = build_conv_layer(
            self.conv_cfg,
            width,
            self.planes * self.expansion,
            kernel_size=1,
            bias=False)
        self.add_module(self.norm3_name, norm3)

        if self.with_plugins:
            self._del_block_plugins(self.after_conv1_plugin_names +
                                    self.after_conv2_plugin_names +
                                    self.after_conv3_plugin_names)
            self.after_conv1_plugin_names = self.make_block_plugins(
                width, self.after_conv1_plugins)
            self.after_conv2_plugin_names = self.make_block_plugins(
                width, self.after_conv2_plugins)
            self.after_conv3_plugin_names = self.make_block_plugins(
                self.planes * self.expansion, self.after_conv3_plugins)

    def _del_block_plugins(self, plugin_names):
        """delete plugins for block if exist.

        Args:
            plugin_names (list[str]): List of plugins name to delete.
        """
        assert isinstance(plugin_names, list)
        for plugin_name in plugin_names:
            del self._modules[plugin_name]


[文档]@BACKBONES.register_module() class ResNeXt(ResNet): """ResNeXt backbone. Args: depth (int): Depth of resnet, from {18, 34, 50, 101, 152}. in_channels (int): Number of input image channels. Default: 3. num_stages (int): Resnet stages. Default: 4. groups (int): Group of resnext. base_width (int): Base width of resnext. strides (Sequence[int]): Strides of the first block of each stage. dilations (Sequence[int]): Dilation of each stage. out_indices (Sequence[int]): Output from which stages. style (str): `pytorch` or `caffe`. If set to "pytorch", the stride-two layer is the 3x3 conv layer, otherwise the stride-two layer is the first 1x1 conv layer. frozen_stages (int): Stages to be frozen (all param fixed). -1 means not freezing any parameters. norm_cfg (dict): dictionary to construct and config norm layer. norm_eval (bool): Whether to set norm layers to eval mode, namely, freeze running stats (mean and var). Note: Effect on Batch Norm and its variants only. with_cp (bool): Use checkpoint or not. Using checkpoint will save some memory while slowing down the training speed. zero_init_residual (bool): whether to use zero init for last norm layer in resblocks to let them behave as identity. """ arch_settings = { 50: (Bottleneck, (3, 4, 6, 3)), 101: (Bottleneck, (3, 4, 23, 3)), 152: (Bottleneck, (3, 8, 36, 3)) } def __init__(self, groups=1, base_width=4, **kwargs): self.groups = groups self.base_width = base_width super(ResNeXt, self).__init__(**kwargs)
[文档] def make_res_layer(self, **kwargs): """Pack all blocks in a stage into a ``ResLayer``""" return ResLayer( groups=self.groups, base_width=self.base_width, base_channels=self.base_channels, **kwargs)
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