quantus.metrics.robustness.continuity module

This module contains the implementation of the Continuity metric.

final class quantus.metrics.robustness.continuity.Continuity(nr_steps: int = 28, abs: bool = True, normalise: bool = True, normalise_func: ~typing.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, normalise_func_kwargs: ~typing.Dict[str, ~typing.Any] | None = None, perturb_func: ~typing.Callable | None = None, perturb_baseline: str = 'black', perturb_func_kwargs: ~typing.Dict[str, ~typing.Any] | None = None, return_aggregate: bool = False, aggregate_func: ~typing.Callable | None = <function mean>, default_plot_func: ~typing.Callable | None = None, disable_warnings: bool = False, display_progressbar: bool = False, return_nan_when_prediction_changes: bool = False, **kwargs)

Bases: Metric[List[float]]

Implementation of the Continuity test by Montavon et al., 2018.

The test measures the strongest variation of the explanation in the input domain i.e., ||R(x) - R(x’)||_1 / ||x - x’||_2 where R(x) is the explanation for input x and x’ is the perturbed input.

Assumptions:

  • The original metric definition relies on perturbation functionality suited only for images.

Therefore, only apply the metric to 3-dimensional (image) data. To extend the applicablity to other data domains, adjustments to the current implementation might be necessary.

References:

1) Grégoire Montavon et al.: “Methods for interpreting and understanding deep neural networks.” Digital Signal Processing 73 (2018): 1-15.

Attributes:

  • _name: The name of the metric.

  • _data_applicability: The data types that the metric implementation currently supports.

  • _models: The model types that this metric can work with.

  • score_direction: How to interpret the scores, whether higher/ lower values are considered better.

  • evaluation_category: What property/ explanation quality that this metric measures.

Attributes:
disable_warnings

A helper to avoid polluting test outputs with warnings.

display_progressbar

A helper to avoid polluting test outputs with tqdm progress bars.

get_params

List parameters of metric.

Methods

__call__(model, x_batch, y_batch[, a_batch, ...])

This implementation represents the main logic of the metric and makes the class object callable.

batch_preprocess(data_batch)

If data_batch has no a_batch, will compute explanations.

custom_batch_preprocess(*, model, x_batch, ...)

Implement this method if you need custom preprocessing of data or simply for creating/initialising additional attributes or assertions before a data_batch can be evaluated.

custom_postprocess(*, model, x_batch, ...)

Implement this method if you need custom postprocessing of results or additional attributes.

custom_preprocess(x_batch, **kwargs)

Implementation of custom_preprocess_batch.

evaluate_batch(model, x_batch, y_batch, **kwargs)

This method performs XAI evaluation on a single batch of explanations.

explain_batch(model, x_batch, y_batch)

Compute explanations, normalise and take absolute (if was configured so during metric initialization.) This method should primarily be used if you need to generate additional explanation in metrics body. It encapsulates typical for Quantus pre- and postprocessing approach. It will do few things: - call model.shape_input (if ModelInterface instance was provided) - unwrap model (if ModelInterface instance was provided) - call explain_func - expand attribution channel - (optionally) normalise a_batch - (optionally) take np.abs of a_batch.

general_preprocess(model, x_batch, y_batch, ...)

Prepares all necessary variables for evaluation.

generate_batches(data, batch_size)

Creates iterator to iterate over all batched instances in data dictionary.

interpret_scores()

Get an interpretation of the scores.

plot([plot_func, show, path_to_save])

Basic plotting functionality for Metric class.
__call__(model, x_batch: ndarray, y_batch: ndarray, a_batch: ndarray | None = None, s_batch: ndarray | None = None, channel_first: bool | None = None, explain_func: Callable | None = None, explain_func_kwargs: Dict | None = None, model_predict_kwargs: Dict | None = None, softmax: bool | None = False, device: str | None = None, batch_size: int = 64, **kwargs) → List[float]

This implementation represents the main logic of the metric and makes the class object callable. It completes instance-wise evaluation of explanations (a_batch) with respect to input data (x_batch), output labels (y_batch) and a torch or tensorflow model (model).

Calls general_preprocess() with all relevant arguments, calls () on each instance, and saves results to evaluation_scores. Calls custom_postprocess() afterwards. Finally returns evaluation_scores.

Parameters:
model: torch.nn.Module, tf.keras.Model

A torch or tensorflow model that is subject to explanation.

x_batch: np.ndarray

A np.ndarray which contains the input data that are explained.

y_batch: np.ndarray

A np.ndarray which contains the output labels that are explained.

a_batch: np.ndarray, optional

A np.ndarray which contains pre-computed attributions i.e., explanations.

s_batch: np.ndarray, optional

A np.ndarray which contains segmentation masks that matches the input.

channel_first: boolean, optional

Indicates of the image dimensions are channel first, or channel last. Inferred from the input shape if None.

explain_func: callable

Callable generating attributions.

explain_func_kwargs: dict, optional

Keyword arguments to be passed to explain_func on call.

model_predict_kwargs: dict, optional

Keyword arguments to be passed to the model’s predict method.

softmax: boolean

Indicates whether to use softmax probabilities or logits in model prediction. This is used for this __call__ only and won’t be saved as attribute. If None, self.softmax is used.

device: string

Indicated the device on which a torch.Tensor is or will be allocated: “cpu” or “gpu”.

kwargs: optional

Keyword arguments.

Returns:
evaluation_scores: list

a list of Any with the evaluation scores of the concerned batch.

Examples:

# Minimal imports. >> import quantus >> from quantus import LeNet >> import torch

# Enable GPU. >> device = torch.device(“cuda:0” if torch.cuda.is_available() else “cpu”)

# Load a pre-trained LeNet classification model (architecture at quantus/helpers/models). >> model = LeNet() >> model.load_state_dict(torch.load(“tutorials/assets/pytests/mnist_model”))

# Load MNIST datasets and make loaders. >> test_set = torchvision.datasets.MNIST(root=’./sample_data’, download=True) >> test_loader = torch.utils.data.DataLoader(test_set, batch_size=24)

# Load a batch of inputs and outputs to use for XAI evaluation. >> x_batch, y_batch = iter(test_loader).next() >> x_batch, y_batch = x_batch.cpu().numpy(), y_batch.cpu().numpy()

# Generate Saliency attributions of the test set batch of the test set. >> a_batch_saliency = Saliency(model).attribute(inputs=x_batch, target=y_batch, abs=True).sum(axis=1) >> a_batch_saliency = a_batch_saliency.cpu().numpy()

# Initialise the metric and evaluate explanations by calling the metric instance. >> metric = Metric(abs=True, normalise=False) >> scores = metric(model=model, x_batch=x_batch, y_batch=y_batch, a_batch=a_batch_saliency)

__init__(nr_steps: int = 28, abs: bool = True, normalise: bool = True, normalise_func: ~typing.Callable[[~numpy.ndarray], ~numpy.ndarray] | None = None, normalise_func_kwargs: ~typing.Dict[str, ~typing.Any] | None = None, perturb_func: ~typing.Callable | None = None, perturb_baseline: str = 'black', perturb_func_kwargs: ~typing.Dict[str, ~typing.Any] | None = None, return_aggregate: bool = False, aggregate_func: ~typing.Callable | None = <function mean>, default_plot_func: ~typing.Callable | None = None, disable_warnings: bool = False, display_progressbar: bool = False, return_nan_when_prediction_changes: bool = False, **kwargs)
Parameters:
patch_size: integer

The patch size for masking, default=7.

nr_steps: integer

The number of steps to iterate over, default=28.

abs: boolean

Indicates whether absolute operation is applied on the attribution, default=True.

normalise: boolean

Indicates whether normalise operation is applied on the attribution, default=True.

normalise_func: callable

Attribution normalisation function applied in case normalise=True. If normalise_func=None, the default value is used, default=normalise_by_max.

normalise_func_kwargs: dict

Keyword arguments to be passed to normalise_func on call, default={}.

perturb_func: callable

Input perturbation function. If None, the default value is used, default=translation_x_direction.

perturb_baseline: string

Indicates the type of baseline: “mean”, “random”, “uniform”, “black” or “white”, default=”black”.

perturb_func_kwargs: dict

Keyword arguments to be passed to perturb_func, default={}.

return_aggregate: boolean

Indicates if an aggregated score should be computed over all instances.

aggregate_func: callable

Callable that aggregates the scores given an evaluation call.

default_plot_func: callable

Callable that plots the metrics result.

disable_warnings: boolean

Indicates whether the warnings are printed, default=False.

display_progressbar: boolean

Indicates whether a tqdm-progress-bar is printed, default=False.

default_plot_func: callable

Callable that plots the metrics result.

return_nan_when_prediction_changes: boolean

When set to true, the metric will be evaluated to NaN if the prediction changes after the perturbation is applied.

kwargs: optional

Keyword arguments.

custom_preprocess(x_batch: ndarray, **kwargs) → None

Implementation of custom_preprocess_batch.

Parameters:
x_batch: np.ndarray

A np.ndarray which contains the input data that are explained.

kwargs:

Unused.

Returns
——-
None.
data_applicability: ClassVar[Set[DataType]] = {DataType.IMAGE}
evaluate_batch(model: ModelInterface, x_batch: ndarray, y_batch: ndarray, **kwargs) → ndarray

This method performs XAI evaluation on a single batch of explanations. For more information on the specific logic, we refer the metric’s initialisation docstring.

Parameters:
model:

A model that is subject to explanation.

x_batch:

A np.ndarray which contains the input data that are explained.

y_batch:

A np.ndarray which contains the output labels that are explained.

kwargs:

Unused.

Returns:
scores_batch:

Evaluation results.

evaluation_category: ClassVar[EvaluationCategory] = 'Robustness'
model_applicability: ClassVar[Set[ModelType]] = {ModelType.TF, ModelType.TORCH}
name: ClassVar[str] = 'Continuity'
score_direction: ClassVar[ScoreDirection] = 'lower'