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Python

""" PyTorch FX Based Feature Extraction Helpers
Using https://pytorch.org/vision/stable/feature_extraction.html
"""
from typing import Callable, Dict, List, Optional, Union, Tuple, Type
import torch
from torch import nn
from timm.layers import (
create_feature_extractor,
get_graph_node_names,
register_notrace_module,
register_notrace_function,
is_notrace_module,
is_notrace_function,
get_notrace_functions,
get_notrace_modules,
Format,
)
from ._features import _get_feature_info, _get_return_layers
__all__ = [
'register_notrace_module',
'is_notrace_module',
'get_notrace_modules',
'register_notrace_function',
'is_notrace_function',
'get_notrace_functions',
'create_feature_extractor',
'get_graph_node_names',
'FeatureGraphNet',
'GraphExtractNet',
]
class FeatureGraphNet(nn.Module):
""" A FX Graph based feature extractor that works with the model feature_info metadata
"""
return_dict: torch.jit.Final[bool]
def __init__(
self,
model: nn.Module,
out_indices: Tuple[int, ...],
out_map: Optional[Dict] = None,
output_fmt: str = 'NCHW',
return_dict: bool = False,
):
super().__init__()
self.feature_info = _get_feature_info(model, out_indices)
if out_map is not None:
assert len(out_map) == len(out_indices)
self.output_fmt = Format(output_fmt)
return_nodes = _get_return_layers(self.feature_info, out_map)
self.graph_module = create_feature_extractor(model, return_nodes)
self.return_dict = return_dict
def forward(self, x):
out = self.graph_module(x)
if self.return_dict:
return out
return list(out.values())
class GraphExtractNet(nn.Module):
""" A standalone feature extraction wrapper that maps dict -> list or single tensor
NOTE:
* one can use feature_extractor directly if dictionary output is desired
* unlike FeatureGraphNet, this is intended to be used standalone and not with model feature_info
metadata for builtin feature extraction mode
* create_feature_extractor can be used directly if dictionary output is acceptable
Args:
model: model to extract features from
return_nodes: node names to return features from (dict or list)
squeeze_out: if only one output, and output in list format, flatten to single tensor
return_dict: return as dictionary from extractor with node names as keys, ignores squeeze_out arg
"""
return_dict: torch.jit.Final[bool]
def __init__(
self,
model: nn.Module,
return_nodes: Union[Dict[str, str], List[str]],
squeeze_out: bool = True,
return_dict: bool = False,
):
super().__init__()
self.squeeze_out = squeeze_out
self.graph_module = create_feature_extractor(model, return_nodes)
self.return_dict = return_dict
def forward(self, x) -> Union[List[torch.Tensor], torch.Tensor]:
out = self.graph_module(x)
if self.return_dict:
return out
out = list(out.values())
return out[0] if self.squeeze_out and len(out) == 1 else out