Merge branch 'regnet' into 'master'

Add RegNet

See merge request open-mmlab/mmclassification!24

.gitlab-ci.yml

@@ -42,4 +42,4 @@ test:pytorch1.3-cuda10:
 
 test:pat0.6.0dev-cuda9:
   image: $PARROTS_IMAGE
-  <<: *test_template_def
+  <<: *test_template_def

mmcls/models/backbones/__init__.py

@@ -1,5 +1,6 @@
 from .mobilenet_v2 import MobileNetV2
 from .mobilenet_v3 import MobileNetv3
+from .regnet import RegNet
 from .resnet import ResNet, ResNetV1d
 from .resnext import ResNeXt
 from .seresnet import SEResNet
@@ -8,6 +9,6 @@ from .shufflenet_v1 import ShuffleNetV1
 from .shufflenet_v2 import ShuffleNetV2
 
 __all__ = [
-    'ResNet', 'ResNeXt', 'ResNetV1d', 'ResNetV1d', 'SEResNet', 'SEResNeXt',
+    'RegNet', 'ResNet', 'ResNeXt', 'ResNetV1d', 'ResNetV1d', 'SEResNet',
-    'ShuffleNetV1', 'ShuffleNetV2', 'MobileNetV2', 'MobileNetv3'
+    'SEResNeXt', 'ShuffleNetV1', 'ShuffleNetV2', 'MobileNetV2', 'MobileNetv3'
 ]

mmcls/models/backbones/regnet.py

@@ -0,0 +1,312 @@
+import numpy as np
+import torch.nn as nn
+from mmcv.cnn import build_conv_layer, build_norm_layer
+
+from ..builder import BACKBONES
+from .resnet import ResNet
+from .resnext import Bottleneck
+
+
+@BACKBONES.register_module()
+class RegNet(ResNet):
+    """RegNet backbone.
+
+    More details can be found in `paper <https://arxiv.org/abs/2003.13678>`_ .
+
+    Args:
+        arch (dict): The parameter of RegNets.
+            - w0 (int): initial width
+            - wa (float): slope of width
+            - wm (float): quantization parameter to quantize the width
+            - depth (int): depth of the backbone
+            - group_w (int): width of group
+            - bot_mul (float): bottleneck ratio, i.e. expansion of bottlneck.
+        strides (Sequence[int]): Strides of the first block of each stage.
+        base_channels (int): Base channels after stem layer.
+        in_channels (int): Number of input image channels. Default: 3.
+        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. Default: "pytorch".
+        frozen_stages (int): Stages to be frozen (all param fixed). -1 means
+            not freezing any parameters. Default: -1.
+        norm_cfg (dict): dictionary to construct and config norm layer.
+            Default: dict(type='BN', requires_grad=True).
+        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. Default: False.
+        with_cp (bool): Use checkpoint or not. Using checkpoint will save some
+            memory while slowing down the training speed. Default: False.
+        zero_init_residual (bool): whether to use zero init for last norm layer
+            in resblocks to let them behave as identity. Default: True.
+
+    Example:
+        >>> from mmdet.models import RegNet
+        >>> import torch
+        >>> self = RegNet(
+                arch=dict(
+                    w0=88,
+                    wa=26.31,
+                    wm=2.25,
+                    group_w=48,
+                    depth=25,
+                    bot_mul=1.0))
+        >>> self.eval()
+        >>> inputs = torch.rand(1, 3, 32, 32)
+        >>> level_outputs = self.forward(inputs)
+        >>> for level_out in level_outputs:
+        ...     print(tuple(level_out.shape))
+        (1, 96, 8, 8)
+        (1, 192, 4, 4)
+        (1, 432, 2, 2)
+        (1, 1008, 1, 1)
+    """
+    arch_settings = {
+        'regnetx_400mf':
+        dict(w0=24, wa=24.48, wm=2.54, group_w=16, depth=22, bot_mul=1.0),
+        'regnetx_800mf':
+        dict(w0=56, wa=35.73, wm=2.28, group_w=16, depth=16, bot_mul=1.0),
+        'regnetx_1.6gf':
+        dict(w0=80, wa=34.01, wm=2.25, group_w=24, depth=18, bot_mul=1.0),
+        'regnetx_3.2gf':
+        dict(w0=88, wa=26.31, wm=2.25, group_w=48, depth=25, bot_mul=1.0),
+        'regnetx_4.0gf':
+        dict(w0=96, wa=38.65, wm=2.43, group_w=40, depth=23, bot_mul=1.0),
+        'regnetx_6.4gf':
+        dict(w0=184, wa=60.83, wm=2.07, group_w=56, depth=17, bot_mul=1.0),
+        'regnetx_8.0gf':
+        dict(w0=80, wa=49.56, wm=2.88, group_w=120, depth=23, bot_mul=1.0),
+        'regnetx_12gf':
+        dict(w0=168, wa=73.36, wm=2.37, group_w=112, depth=19, bot_mul=1.0),
+    }
+
+    def __init__(self,
+                 arch,
+                 in_channels=3,
+                 stem_channels=32,
+                 base_channels=32,
+                 strides=(2, 2, 2, 2),
+                 dilations=(1, 1, 1, 1),
+                 out_indices=(3, ),
+                 style='pytorch',
+                 deep_stem=False,
+                 avg_down=False,
+                 frozen_stages=-1,
+                 conv_cfg=None,
+                 norm_cfg=dict(type='BN', requires_grad=True),
+                 norm_eval=False,
+                 with_cp=False,
+                 zero_init_residual=True):
+        super(ResNet, self).__init__()
+
+        # Generate RegNet parameters first
+        if isinstance(arch, str):
+            assert arch in self.arch_settings, \
+                f'"arch": "{arch}" is not one of the' \
+                ' arch_settings'
+            arch = self.arch_settings[arch]
+        elif not isinstance(arch, dict):
+            raise TypeError('Expect "arch" to be either a string '
+                            f'or a dict, got {type(arch)}')
+
+        widths, num_stages = self.generate_regnet(
+            arch['w0'],
+            arch['wa'],
+            arch['wm'],
+            arch['depth'],
+        )
+        # Convert to per stage format
+        stage_widths, stage_blocks = self.get_stages_from_blocks(widths)
+        # Generate group widths and bot muls
+        group_widths = [arch['group_w'] for _ in range(num_stages)]
+        self.bottleneck_ratio = [arch['bot_mul'] for _ in range(num_stages)]
+        # Adjust the compatibility of stage_widths and group_widths
+        stage_widths, group_widths = self.adjust_width_group(
+            stage_widths, self.bottleneck_ratio, group_widths)
+
+        # Group params by stage
+        self.stage_widths = stage_widths
+        self.group_widths = group_widths
+        self.depth = sum(stage_blocks)
+        self.stem_channels = stem_channels
+        self.base_channels = base_channels
+        self.num_stages = num_stages
+        assert num_stages >= 1 and num_stages <= 4
+        self.strides = strides
+        self.dilations = dilations
+        assert len(strides) == len(dilations) == num_stages
+        self.out_indices = out_indices
+        assert max(out_indices) < num_stages
+        self.style = style
+        self.deep_stem = deep_stem
+        if self.deep_stem:
+            raise NotImplementedError(
+                'deep_stem has not been implemented for RegNet')
+        self.avg_down = avg_down
+        self.frozen_stages = frozen_stages
+        self.conv_cfg = conv_cfg
+        self.norm_cfg = norm_cfg
+        self.with_cp = with_cp
+        self.norm_eval = norm_eval
+        self.zero_init_residual = zero_init_residual
+        self.stage_blocks = stage_blocks[:num_stages]
+
+        self._make_stem_layer(in_channels, stem_channels)
+
+        _in_channels = stem_channels
+        self.res_layers = []
+        for i, num_blocks in enumerate(self.stage_blocks):
+            stride = self.strides[i]
+            dilation = self.dilations[i]
+            group_width = self.group_widths[i]
+            width = int(round(self.stage_widths[i] * self.bottleneck_ratio[i]))
+            stage_groups = width // group_width
+
+            res_layer = self.make_res_layer(
+                block=Bottleneck,
+                num_blocks=num_blocks,
+                in_channels=_in_channels,
+                out_channels=self.stage_widths[i],
+                expansion=1,
+                stride=stride,
+                dilation=dilation,
+                style=self.style,
+                avg_down=self.avg_down,
+                with_cp=self.with_cp,
+                conv_cfg=self.conv_cfg,
+                norm_cfg=self.norm_cfg,
+                base_channels=self.stage_widths[i],
+                groups=stage_groups,
+                width_per_group=group_width)
+            _in_channels = self.stage_widths[i]
+            layer_name = f'layer{i + 1}'
+            self.add_module(layer_name, res_layer)
+            self.res_layers.append(layer_name)
+
+        self._freeze_stages()
+
+        self.feat_dim = stage_widths[-1]
+
+    def _make_stem_layer(self, in_channels, base_channels):
+        self.conv1 = build_conv_layer(
+            self.conv_cfg,
+            in_channels,
+            base_channels,
+            kernel_size=3,
+            stride=2,
+            padding=1,
+            bias=False)
+        self.norm1_name, norm1 = build_norm_layer(
+            self.norm_cfg, base_channels, postfix=1)
+        self.add_module(self.norm1_name, norm1)
+        self.relu = nn.ReLU(inplace=True)
+
+    def generate_regnet(self,
+                        initial_width,
+                        width_slope,
+                        width_parameter,
+                        depth,
+                        divisor=8):
+        """Generates per block width from RegNet parameters.
+
+        Args:
+            initial_width ([int]): Initial width of the backbone
+            width_slope ([float]): Slope of the quantized linear function
+            width_parameter ([int]): Parameter used to quantize the width.
+            depth ([int]): Depth of the backbone.
+            divisor (int, optional): The divisor of channels. Defaults to 8.
+
+        Returns:
+            list, int: return a list of widths of each stage and the number of
+                stages
+        """
+        assert width_slope >= 0
+        assert initial_width > 0
+        assert width_parameter > 1
+        assert initial_width % divisor == 0
+        widths_cont = np.arange(depth) * width_slope + initial_width
+        ks = np.round(
+            np.log(widths_cont / initial_width) / np.log(width_parameter))
+        widths = initial_width * np.power(width_parameter, ks)
+        widths = np.round(np.divide(widths, divisor)) * divisor
+        num_stages = len(np.unique(widths))
+        widths, widths_cont = widths.astype(int).tolist(), widths_cont.tolist()
+        return widths, num_stages
+
+    @staticmethod
+    def quantize_float(number, divisor):
+        """Converts a float to closest non-zero int divisible by divior.
+
+        Args:
+            number (int): Original number to be quantized.
+            divisor (int): Divisor used to quantize the number.
+
+        Returns:
+            int: quantized number that is divisible by devisor.
+        """
+        return int(round(number / divisor) * divisor)
+
+    def adjust_width_group(self, widths, bottleneck_ratio, groups):
+        """Adjusts the compatibility of widths and groups.
+
+        Args:
+            widths (list[int]): Width of each stage.
+            bottleneck_ratio (float): Bottleneck ratio.
+            groups (int): number of groups in each stage
+
+        Returns:
+            tuple(list): The adjusted widths and groups of each stage.
+        """
+        bottleneck_width = [
+            int(w * b) for w, b in zip(widths, bottleneck_ratio)
+        ]
+        groups = [min(g, w_bot) for g, w_bot in zip(groups, bottleneck_width)]
+        bottleneck_width = [
+            self.quantize_float(w_bot, g)
+            for w_bot, g in zip(bottleneck_width, groups)
+        ]
+        widths = [
+            int(w_bot / b)
+            for w_bot, b in zip(bottleneck_width, bottleneck_ratio)
+        ]
+        return widths, groups
+
+    def get_stages_from_blocks(self, widths):
+        """Gets widths/stage_blocks of network at each stage
+
+        Args:
+            widths (list[int]): Width in each stage.
+
+        Returns:
+            tuple(list): width and depth of each stage
+        """
+        width_diff = [
+            width != width_prev
+            for width, width_prev in zip(widths + [0], [0] + widths)
+        ]
+        stage_widths = [
+            width for width, diff in zip(widths, width_diff[:-1]) if diff
+        ]
+        stage_blocks = np.diff([
+            depth for depth, diff in zip(range(len(width_diff)), width_diff)
+            if diff
+        ]).tolist()
+        return stage_widths, stage_blocks
+
+    def forward(self, x):
+        x = self.conv1(x)
+        x = self.norm1(x)
+        x = self.relu(x)
+
+        outs = []
+        for i, layer_name in enumerate(self.res_layers):
+            res_layer = getattr(self, layer_name)
+            x = res_layer(x)
+            if i in self.out_indices:
+                outs.append(x)
+
+        if len(outs) == 1:
+            return outs[0]
+        else:
+            return tuple(outs)

tests/test_backbones/test_regnet.py

@@ -0,0 +1,91 @@
+import pytest
+import torch
+
+from mmcls.models.backbones import RegNet
+
+regnet_test_data = [
+    ('regnetx_400mf',
+     dict(w0=24, wa=24.48, wm=2.54, group_w=16, depth=22,
+          bot_mul=1.0), [32, 64, 160, 384]),
+    ('regnetx_800mf',
+     dict(w0=56, wa=35.73, wm=2.28, group_w=16, depth=16,
+          bot_mul=1.0), [64, 128, 288, 672]),
+    ('regnetx_1.6gf',
+     dict(w0=80, wa=34.01, wm=2.25, group_w=24, depth=18,
+          bot_mul=1.0), [72, 168, 408, 912]),
+    ('regnetx_3.2gf',
+     dict(w0=88, wa=26.31, wm=2.25, group_w=48, depth=25,
+          bot_mul=1.0), [96, 192, 432, 1008]),
+    ('regnetx_4.0gf',
+     dict(w0=96, wa=38.65, wm=2.43, group_w=40, depth=23,
+          bot_mul=1.0), [80, 240, 560, 1360]),
+    ('regnetx_6.4gf',
+     dict(w0=184, wa=60.83, wm=2.07, group_w=56, depth=17,
+          bot_mul=1.0), [168, 392, 784, 1624]),
+    ('regnetx_8.0gf',
+     dict(w0=80, wa=49.56, wm=2.88, group_w=120, depth=23,
+          bot_mul=1.0), [80, 240, 720, 1920]),
+    ('regnetx_12gf',
+     dict(w0=168, wa=73.36, wm=2.37, group_w=112, depth=19,
+          bot_mul=1.0), [224, 448, 896, 2240]),
+]
+
+
+@pytest.mark.parametrize('arch_name,arch,out_channels', regnet_test_data)
+def test_regnet_backbone(arch_name, arch, out_channels):
+    with pytest.raises(AssertionError):
+        # ResNeXt depth should be in [50, 101, 152]
+        RegNet(arch_name + '233')
+
+    # output the last feature map
+    model = RegNet(arch_name)
+    model.init_weights()
+    model.train()
+
+    imgs = torch.randn(1, 3, 224, 224)
+    feat = model(imgs)
+    assert isinstance(feat, torch.Tensor)
+    assert feat.shape == (1, out_channels[-1], 7, 7)
+
+    # output feature map of all stages
+    model = RegNet(arch_name, out_indices=(0, 1, 2, 3))
+    model.init_weights()
+    model.train()
+
+    imgs = torch.randn(1, 3, 224, 224)
+    feat = model(imgs)
+    assert len(feat) == 4
+    assert feat[0].shape == (1, out_channels[0], 56, 56)
+    assert feat[1].shape == (1, out_channels[1], 28, 28)
+    assert feat[2].shape == (1, out_channels[2], 14, 14)
+    assert feat[3].shape == (1, out_channels[3], 7, 7)
+
+
+@pytest.mark.parametrize('arch_name,arch,out_channels', regnet_test_data)
+def test_custom_arch(arch_name, arch, out_channels):
+    # output the last feature map
+    model = RegNet(arch)
+    model.init_weights()
+
+    imgs = torch.randn(1, 3, 224, 224)
+    feat = model(imgs)
+    assert isinstance(feat, torch.Tensor)
+    assert feat.shape == (1, out_channels[-1], 7, 7)
+
+    # output feature map of all stages
+    model = RegNet(arch, out_indices=(0, 1, 2, 3))
+    model.init_weights()
+
+    imgs = torch.randn(1, 3, 224, 224)
+    feat = model(imgs)
+    assert len(feat) == 4
+    assert feat[0].shape == (1, out_channels[0], 56, 56)
+    assert feat[1].shape == (1, out_channels[1], 28, 28)
+    assert feat[2].shape == (1, out_channels[2], 14, 14)
+    assert feat[3].shape == (1, out_channels[3], 7, 7)
+
+
+def test_exception():
+    # arch must be a str or dict
+    with pytest.raises(TypeError):
+        _ = RegNet(50)