114 lines
4.3 KiB
Python
114 lines
4.3 KiB
Python
# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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from collections import OrderedDict
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import paddle
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from paddle import nn
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def _make_divisible(v, divisor=8, min_value=None):
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"""
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This function ensures that all layers have a channel number that is divisible by divisor.
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You can also see at https://github.com/keras-team/keras/blob/8ecef127f70db723c158dbe9ed3268b3d610ab55/keras/applications/mobilenet_v2.py#L505
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Args:
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divisor (int, optional): The divisor for number of channels. Default: 8.
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min_value (int, optional): The minimum value of number of channels, if it is None,
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the default is divisor. Default: None.
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"""
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if min_value is None:
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min_value = divisor
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new_v = max(min_value, int(v + divisor / 2) // divisor * divisor)
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# Make sure that round down does not go down by more than 10%.
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if new_v < 0.9 * v:
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new_v += divisor
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return new_v
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class IntermediateLayerGetter(nn.LayerDict):
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"""
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Layer wrapper that returns intermediate layers from a model.
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It has a strong assumption that the layers have been registered into the model in the
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same order as they are used. This means that one should **not** reuse the same nn.Layer
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twice in the forward if you want this to work.
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Additionally, it is only able to query sublayer that are directly assigned to the model.
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So if `model` is passed, `model.feature1` can be returned, but not `model.feature1.layer2`.
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Args:
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model (nn.Layer): Model on which we will extract the features.
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return_layers (Dict[name, new_name]): A dict containing the names of the layers for
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which the activations will be returned as the key of the dict, and the value of the
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dict is the name of the returned activation (which the user can specify).
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Examples:
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.. code-block:: pycon
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>>> import paddle
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>>> m = paddle.vision.models.resnet18(pretrained=False)
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>>> # extract layer1 and layer3, giving as names `feat1` and feat2`
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>>> new_m = paddle.vision.models._utils.IntermediateLayerGetter(
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... m,
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... {
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... 'layer1': 'feat1',
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... 'layer3': 'feat2',
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... },
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... )
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>>> out = new_m(paddle.rand([1, 3, 224, 224]))
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>>> print([(k, v.shape) for k, v in out.items()])
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[('feat1', [1, 64, 56, 56]), ('feat2', [1, 256, 14, 14])]
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"""
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return_layers: dict[str, str]
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def __init__(self, model: nn.Layer, return_layers: dict[str, str]) -> None:
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if not set(return_layers).issubset(
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[name for name, _ in model.named_children()]
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):
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raise ValueError("return_layers are not present in model")
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orig_return_layers = return_layers
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return_layers = {str(k): str(v) for k, v in return_layers.items()}
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layers = OrderedDict()
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for name, module in model.named_children():
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layers[name] = module
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if name in return_layers:
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del return_layers[name]
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if not return_layers:
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break
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super().__init__(layers)
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self.return_layers = orig_return_layers
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def forward(self, x):
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out = OrderedDict()
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for name, module in self.items():
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if (isinstance(module, nn.Linear) and x.ndim == 4) or (
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len(module.sublayers()) > 0
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and isinstance(module.sublayers()[0], nn.Linear)
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and x.ndim == 4
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):
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x = paddle.flatten(x, 1)
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x = module(x)
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if name in self.return_layers:
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out_name = self.return_layers[name]
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out[out_name] = x
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return out
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