#!/usr/bin/env python3
from typing import Any, Callable, List, Tuple, Union
from captum._utils.gradient import construct_neuron_grad_fn
from captum._utils.typing import TensorOrTupleOfTensorsGeneric
from captum.attr._core.guided_backprop_deconvnet import Deconvolution, GuidedBackprop
from captum.attr._utils.attribution import GradientAttribution, NeuronAttribution
from captum.log import log_usage
from torch.nn import Module
[docs]
class NeuronDeconvolution(NeuronAttribution, GradientAttribution):
r"""
Computes attribution of the given neuron using deconvolution.
Deconvolution computes the gradient of the target output with
respect to the input, but gradients of ReLU functions are overridden so
that the gradient of the ReLU input is simply computed taking ReLU of
the output gradient, essentially only propagating non-negative gradients
(without dependence on the sign of the ReLU input).
More details regarding the deconvolution algorithm can be found
in these papers:
https://arxiv.org/abs/1311.2901
https://link.springer.com/chapter/10.1007/978-3-319-46466-4_8
Warning: Ensure that all ReLU operations in the forward function of the
given model are performed using a module (nn.module.ReLU).
If nn.functional.ReLU is used, gradients are not overridden appropriately.
"""
def __init__(
self, model: Module, layer: Module, device_ids: Union[None, List[int]] = None
) -> None:
r"""
Args:
model (nn.Module): The reference to PyTorch model instance.
layer (Module): Layer for which attributions are computed.
Output size of attribute matches this layer's input or
output dimensions, depending on whether we attribute to
the inputs or outputs of the layer, corresponding to
attribution of each neuron in the input or output of
this layer.
Currently, it is assumed that the inputs or the outputs
of the layer, depending on which one is used for
attribution, can only be a single tensor.
device_ids (list[int]): Device ID list, necessary only if model
applies a DataParallel model. This allows reconstruction of
intermediate outputs from batched results across devices.
If model is given as the DataParallel model itself,
then it is not necessary to provide this argument.
"""
NeuronAttribution.__init__(self, model, layer, device_ids)
GradientAttribution.__init__(self, model)
self.deconv = Deconvolution(model)
[docs]
@log_usage()
def attribute(
self,
inputs: TensorOrTupleOfTensorsGeneric,
neuron_selector: Union[int, Tuple[Union[int, slice], ...], Callable],
additional_forward_args: Any = None,
attribute_to_neuron_input: bool = False,
) -> TensorOrTupleOfTensorsGeneric:
r"""
Args:
inputs (Tensor or tuple[Tensor, ...]): Input for which
attributions are computed. If model takes a single
tensor as input, a single input tensor should be provided.
If model takes multiple tensors as input, a tuple
of the input tensors should be provided. It is assumed
that for all given input tensors, dimension 0 corresponds
to the number of examples (aka batch size), and if
multiple input tensors are provided, the examples must
be aligned appropriately.
neuron_selector (int, Callable, tuple[int], or slice):
Selector for neuron
in given layer for which attribution is desired.
Neuron selector can be provided as:
- a single integer, if the layer output is 2D. This integer
selects the appropriate neuron column in the layer input
or output
- a tuple of integers or slice objects. Length of this
tuple must be one less than the number of dimensions
in the input / output of the given layer (since
dimension 0 corresponds to number of examples).
The elements of the tuple can be either integers or
slice objects (slice object allows indexing a
range of neurons rather individual ones).
If any of the tuple elements is a slice object, the
indexed output tensor is used for attribution. Note
that specifying a slice of a tensor would amount to
computing the attribution of the sum of the specified
neurons, and not the individual neurons independently.
- a callable, which should
take the target layer as input (single tensor or tuple
if multiple tensors are in layer) and return a neuron or
aggregate of the layer's neurons for attribution.
For example, this function could return the
sum of the neurons in the layer or sum of neurons with
activations in a particular range. It is expected that
this function returns either a tensor with one element
or a 1D tensor with length equal to batch_size (one scalar
per input example)
additional_forward_args (Any, optional): If the forward function
requires additional arguments other than the inputs for
which attributions should not be computed, this argument
can be provided. It must be either a single additional
argument of a Tensor or arbitrary (non-tuple) type or a tuple
containing multiple additional arguments including tensors
or any arbitrary python types. These arguments are provided to
model in order, following the arguments in inputs.
Note that attributions are not computed with respect
to these arguments.
Default: None
attribute_to_neuron_input (bool, optional): Indicates whether to
compute the attributions with respect to the neuron input
or output. If `attribute_to_neuron_input` is set to True
then the attributions will be computed with respect to
neuron's inputs, otherwise it will be computed with respect
to neuron's outputs.
Note that currently it is assumed that either the input
or the output of internal neuron, depending on whether we
attribute to the input or output, is a single tensor.
Support for multiple tensors will be added later.
Default: False
Returns:
*Tensor* or *tuple[Tensor, ...]* of **attributions**:
- **attributions** (*Tensor* or *tuple[Tensor, ...]*):
Deconvolution attribution of
particular neuron with respect to each input feature.
Attributions will always be the same size as the provided
inputs, with each value providing the attribution of the
corresponding input index.
If a single tensor is provided as inputs, a single tensor is
returned. If a tuple is provided for inputs, a tuple of
corresponding sized tensors is returned.
Examples::
>>> # ImageClassifier takes a single input tensor of images Nx3x32x32,
>>> # and returns an Nx10 tensor of class probabilities.
>>> # It contains an attribute conv1, which is an instance of nn.conv2d,
>>> # and the output of this layer has dimensions Nx12x32x32.
>>> net = ImageClassifier()
>>> neuron_deconv = NeuronDeconvolution(net, net.conv1)
>>> input = torch.randn(2, 3, 32, 32, requires_grad=True)
>>> # To compute neuron attribution, we need to provide the neuron
>>> # index for which attribution is desired. Since the layer output
>>> # is Nx12x32x32, we need a tuple in the form (0..11,0..31,0..31)
>>> # which indexes a particular neuron in the layer output.
>>> # For this example, we choose the index (4,1,2).
>>> # Computes neuron deconvolution for neuron with
>>> # index (4,1,2).
>>> attribution = neuron_deconv.attribute(input, (4,1,2))
"""
self.deconv.gradient_func = construct_neuron_grad_fn(
self.layer, neuron_selector, self.device_ids, attribute_to_neuron_input
)
# NOTE: using __wrapped__ to not log
return self.deconv.attribute.__wrapped__(
self.deconv, inputs, None, additional_forward_args
)
[docs]
class NeuronGuidedBackprop(NeuronAttribution, GradientAttribution):
r"""
Computes attribution of the given neuron using guided backpropagation.
Guided backpropagation computes the gradient of the target neuron
with respect to the input, but gradients of ReLU functions are overridden
so that only non-negative gradients are backpropagated.
More details regarding the guided backpropagation algorithm can be found
in the original paper here:
https://arxiv.org/abs/1412.6806
Warning: Ensure that all ReLU operations in the forward function of the
given model are performed using a module (nn.module.ReLU).
If nn.functional.ReLU is used, gradients are not overridden appropriately.
"""
def __init__(
self, model: Module, layer: Module, device_ids: Union[None, List[int]] = None
) -> None:
r"""
Args:
model (nn.Module): The reference to PyTorch model instance.
layer (Module): Layer for which neuron attributions are computed.
Attributions for a particular neuron in the output of
this layer are computed using the argument neuron_selector
in the attribute method.
Currently, only layers with a single tensor output are
supported.
device_ids (list[int]): Device ID list, necessary only if model
applies a DataParallel model. This allows reconstruction of
intermediate outputs from batched results across devices.
If model is given as the DataParallel model itself,
then it is not necessary to provide this argument.
"""
NeuronAttribution.__init__(self, model, layer, device_ids)
GradientAttribution.__init__(self, model)
self.guided_backprop = GuidedBackprop(model)
[docs]
@log_usage()
def attribute(
self,
inputs: TensorOrTupleOfTensorsGeneric,
neuron_selector: Union[int, Tuple[Union[int, slice], ...], Callable],
additional_forward_args: Any = None,
attribute_to_neuron_input: bool = False,
) -> TensorOrTupleOfTensorsGeneric:
r"""
Args:
inputs (Tensor or tuple[Tensor, ...]): Input for which
attributions are computed. If model takes a single
tensor as input, a single input tensor should be provided.
If model takes multiple tensors as input, a tuple
of the input tensors should be provided. It is assumed
that for all given input tensors, dimension 0 corresponds
to the number of examples (aka batch size), and if
multiple input tensors are provided, the examples must
be aligned appropriately.
neuron_selector (int, Callable, tuple[int], or slice):
Selector for neuron
in given layer for which attribution is desired.
Neuron selector can be provided as:
- a single integer, if the layer output is 2D. This integer
selects the appropriate neuron column in the layer input
or output
- a tuple of integers or slice objects. Length of this
tuple must be one less than the number of dimensions
in the input / output of the given layer (since
dimension 0 corresponds to number of examples).
The elements of the tuple can be either integers or
slice objects (slice object allows indexing a
range of neurons rather individual ones).
If any of the tuple elements is a slice object, the
indexed output tensor is used for attribution. Note
that specifying a slice of a tensor would amount to
computing the attribution of the sum of the specified
neurons, and not the individual neurons independently.
- a callable, which should
take the target layer as input (single tensor or tuple
if multiple tensors are in layer) and return a neuron or
aggregate of the layer's neurons for attribution.
For example, this function could return the
sum of the neurons in the layer or sum of neurons with
activations in a particular range. It is expected that
this function returns either a tensor with one element
or a 1D tensor with length equal to batch_size (one scalar
per input example)
additional_forward_args (Any, optional): If the forward function
requires additional arguments other than the inputs for
which attributions should not be computed, this argument
can be provided. It must be either a single additional
argument of a Tensor or arbitrary (non-tuple) type or a tuple
containing multiple additional arguments including tensors
or any arbitrary python types. These arguments are provided to
model in order, following the arguments in inputs.
Note that attributions are not computed with respect
to these arguments.
Default: None
attribute_to_neuron_input (bool, optional): Indicates whether to
compute the attributions with respect to the neuron input
or output. If `attribute_to_neuron_input` is set to True
then the attributions will be computed with respect to
neuron's inputs, otherwise it will be computed with respect
to neuron's outputs.
Note that currently it is assumed that either the input
or the output of internal neurons, depending on whether we
attribute to the input or output, is a single tensor.
Support for multiple tensors will be added later.
Default: False
Returns:
*Tensor* or *tuple[Tensor, ...]* of **attributions**:
- **attributions** (*Tensor* or *tuple[Tensor, ...]*):
Guided backprop attribution of
particular neuron with respect to each input feature.
Attributions will always be the same size as the provided
inputs, with each value providing the attribution of the
corresponding input index.
If a single tensor is provided as inputs, a single tensor is
returned. If a tuple is provided for inputs, a tuple of
corresponding sized tensors is returned.
Examples::
>>> # ImageClassifier takes a single input tensor of images Nx3x32x32,
>>> # and returns an Nx10 tensor of class probabilities.
>>> # It contains an attribute conv1, which is an instance of nn.conv2d,
>>> # and the output of this layer has dimensions Nx12x32x32.
>>> net = ImageClassifier()
>>> neuron_gb = NeuronGuidedBackprop(net, net.conv1)
>>> input = torch.randn(2, 3, 32, 32, requires_grad=True)
>>> # To compute neuron attribution, we need to provide the neuron
>>> # index for which attribution is desired. Since the layer output
>>> # is Nx12x32x32, we need a tuple in the form (0..11,0..31,0..31)
>>> # which indexes a particular neuron in the layer output.
>>> # For this example, we choose the index (4,1,2).
>>> # Computes neuron guided backpropagation for neuron with
>>> # index (4,1,2).
>>> attribution = neuron_gb.attribute(input, (4,1,2))
"""
self.guided_backprop.gradient_func = construct_neuron_grad_fn(
self.layer, neuron_selector, self.device_ids, attribute_to_neuron_input
)
# NOTE: using __wrapped__ to not log
return self.guided_backprop.attribute.__wrapped__(
self.guided_backprop, inputs, None, additional_forward_args
)
