art.estimators.certification.randomized_smoothing
¶
Randomized smoothing estimators.
Mixin Base Class Randomized Smoothing¶

class
art.estimators.certification.randomized_smoothing.
RandomizedSmoothingMixin
(sample_size: int, *args, scale: float = 0.1, alpha: float = 0.001, **kwargs)¶ Implementation of Randomized Smoothing applied to classifier predictions and gradients, as introduced in Cohen et al. (2019).
Paper link: https://arxiv.org/abs/1902.02918
certify
(x: numpy.ndarray, n: int, batch_size: int = 32) → Tuple[numpy.ndarray, numpy.ndarray]¶ Computes certifiable radius around input x and returns radius r and prediction.
 Return type
Tuple
 Parameters
x (
ndarray
) – Sample input with shape as expected by the model.n (
int
) – Number of samples for estimate certifiable radius.batch_size (
int
) – Batch size.
 Returns
Tuple of length 2 of the selected class and certified radius.

fit
(x: numpy.ndarray, y: numpy.ndarray, batch_size: int = 128, nb_epochs: int = 10, **kwargs) → None¶ Fit the classifier on the training set (x, y).
 Parameters
x (
ndarray
) – Training data.y (
ndarray
) – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).batch_size (
int
) – Batch size.nb_epochs (
int
) – Number of epochs to use for training.kwargs – Dictionary of frameworkspecific arguments. This parameter is not currently supported for PyTorch and providing it takes no effect.

predict
(x: numpy.ndarray, batch_size: int = 128, **kwargs) → numpy.ndarray¶ Perform prediction of the given classifier for a batch of inputs, taking an expectation over transformations.
 Return type
ndarray
 Parameters
x (
ndarray
) – Test set.batch_size (
int
) – Batch size.is_abstain (boolean) – True if function will abstain from prediction and return 0s. Default: True
 Returns
Array of predictions of shape (nb_inputs, nb_classes).

PyTorch Randomized Smoothing Classifier¶

class
art.estimators.certification.randomized_smoothing.
PyTorchRandomizedSmoothing
(model: torch.nn.Module, loss: torch.nn.modules.loss._Loss, input_shape: Tuple[int, …], nb_classes: int, optimizer: Optional[torch.optim.Optimizer] = None, channels_first: bool = True, clip_values: Optional[CLIP_VALUES_TYPE] = None, preprocessing_defences: Optional[Union[Preprocessor, List[Preprocessor]]] = None, postprocessing_defences: Optional[Union[Postprocessor, List[Postprocessor]]] = None, preprocessing: PREPROCESSING_TYPE = (0, 1), device_type: str = 'gpu', sample_size: int = 32, scale: float = 0.1, alpha: float = 0.001)¶ Implementation of Randomized Smoothing applied to classifier predictions and gradients, as introduced in Cohen et al. (2019).
Paper link: https://arxiv.org/abs/1902.02918
__init__
(model: torch.nn.Module, loss: torch.nn.modules.loss._Loss, input_shape: Tuple[int, …], nb_classes: int, optimizer: Optional[torch.optim.Optimizer] = None, channels_first: bool = True, clip_values: Optional[CLIP_VALUES_TYPE] = None, preprocessing_defences: Optional[Union[Preprocessor, List[Preprocessor]]] = None, postprocessing_defences: Optional[Union[Postprocessor, List[Postprocessor]]] = None, preprocessing: PREPROCESSING_TYPE = (0, 1), device_type: str = 'gpu', sample_size: int = 32, scale: float = 0.1, alpha: float = 0.001)¶ Create a randomized smoothing classifier.
 Parameters
model – PyTorch model. The output of the model can be logits, probabilities or anything else. Logits output should be preferred where possible to ensure attack efficiency.
loss – The loss function for which to compute gradients for training. The target label must be raw categorical, i.e. not converted to onehot encoding.
input_shape (
Tuple
) – The shape of one input instance.nb_classes (
int
) – The number of classes of the model.optimizer – The optimizer used to train the classifier.
channels_first (
bool
) – Set channels first or last.clip_values – Tuple of the form (min, max) of floats or np.ndarray representing the minimum and maximum values allowed for features. If floats are provided, these will be used as the range of all features. If arrays are provided, each value will be considered the bound for a feature, thus the shape of clip values needs to match the total number of features.
preprocessing_defences – Preprocessing defence(s) to be applied by the classifier.
postprocessing_defences – Postprocessing defence(s) to be applied by the classifier.
preprocessing – Tuple of the form (subtrahend, divisor) of floats or np.ndarray of values to be used for data preprocessing. The first value will be subtracted from the input. The input will then be divided by the second one.
device_type (
str
) – Type of device on which the classifier is run, either gpu or cpu.sample_size (
int
) – Number of samples for smoothing.scale (
float
) – Standard deviation of Gaussian noise added.alpha (
float
) – The failure probability of smoothing.

certify
(x: numpy.ndarray, n: int, batch_size: int = 32) → Tuple[numpy.ndarray, numpy.ndarray]¶ Computes certifiable radius around input x and returns radius r and prediction.
 Return type
Tuple
 Parameters
x (
ndarray
) – Sample input with shape as expected by the model.n (
int
) – Number of samples for estimate certifiable radius.batch_size (
int
) – Batch size.
 Returns
Tuple of length 2 of the selected class and certified radius.

property
channel_index
¶  Returns
Index of the axis containing the color channels in the samples x.

property
channels_first
¶  Returns
Boolean to indicate index of the color channels in the sample x.

class_gradient
(*args, **kwargs)¶ Compute perclass derivatives of the given classifier w.r.t. x of original classifier.
 Parameters
x – Sample input with shape as expected by the model.
label – Index of a specific perclass derivative. If an integer is provided, the gradient of that class output is computed for all samples. If multiple values as provided, the first dimension should match the batch size of x, and each value will be used as target for its corresponding sample in x. If None, then gradients for all classes will be computed for each sample.
 Returns
Array of gradients of input features w.r.t. each class in the form (batch_size, nb_classes, input_shape) when computing for all classes, otherwise shape becomes (batch_size, 1, input_shape) when label parameter is specified.

property
clip_values
¶ Return the clip values of the input samples.
 Returns
Clip values (min, max).

property
device
¶ Get current used device.
 Returns
Current used device.

fit
(*args, **kwargs)¶ Fit the classifier on the training set (x, y).
 Parameters
x – Training data.
y – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
batch_size – Batch size.
kwargs (dict) – Dictionary of frameworkspecific arguments. This parameter is not currently supported for PyTorch and providing it takes no effect.
 Key nb_epochs
Number of epochs to use for training
 Returns
None

fit_generator
(generator: DataGenerator, nb_epochs: int = 20, **kwargs) → None¶ Fit the classifier using the generator that yields batches as specified.
 Parameters
generator – Batch generator providing (x, y) for each epoch.
nb_epochs (
int
) – Number of epochs to use for training.kwargs – Dictionary of frameworkspecific arguments. This parameter is not currently supported for PyTorch and providing it takes no effect.

get_activations
(*args, **kwargs)¶ Return the output of the specified layer for input x. layer is specified by layer index (between 0 and nb_layers  1) or by name. The number of layers can be determined by counting the results returned by calling layer_names.
 Parameters
x – Input for computing the activations.
layer – Layer for computing the activations
batch_size – Size of batches.
framework – If true, return the intermediate tensor representation of the activation.
 Returns
The output of layer, where the first dimension is the batch size corresponding to x.

get_params
() → Dict[str, Any]¶ Get all parameters and their values of this estimator.
 Returns
A dictionary of string parameter names to their value.

property
input_shape
¶ Return the shape of one input sample.
 Returns
Shape of one input sample.

property
layer_names
¶ Return the names of the hidden layers in the model, if applicable.
 Returns
The names of the hidden layers in the model, input and output layers are ignored.
Warning
layer_names tries to infer the internal structure of the model. This feature comes with no guarantees on the correctness of the result. The intended order of the layers tries to match their order in the model, but this is not guaranteed either.

property
learning_phase
¶ The learning phase set by the user. Possible values are True for training or False for prediction and None if it has not been set by the library. In the latter case, the library does not do any explicit learning phase manipulation and the current value of the backend framework is used. If a value has been set by the user for this property, it will impact all following computations for model fitting, prediction and gradients.
 Returns
Learning phase.

loss
(x: numpy.ndarray, y: numpy.ndarray, **kwargs) → numpy.ndarray¶ Compute the loss of the neural network for samples x.
 Parameters
x (
ndarray
) – Samples of shape (nb_samples, nb_features) or (nb_samples, nb_pixels_1, nb_pixels_2, nb_channels) or (nb_samples, nb_channels, nb_pixels_1, nb_pixels_2).y (
ndarray
) – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
 Returns
Loss values.
 Return type
Format as expected by the model

loss_gradient
(*args, **kwargs)¶ Compute the gradient of the loss function w.r.t. x.
 Parameters
x – Sample input with shape as expected by the model.
y – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
sampling (bool) – True if loss gradients should be determined with Monte Carlo sampling.
 Returns
Array of gradients of the same shape as x.

loss_gradient_framework
(x: torch.Tensor, y: torch.Tensor, **kwargs) → torch.Tensor¶ Compute the gradient of the loss function w.r.t. x.
 Parameters
x – Input with shape as expected by the model.
y – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
 Returns
Gradients of the same shape as x.

property
model
¶ Return the model.
 Returns
The model.

property
nb_classes
¶ Return the number of output classes.
 Returns
Number of classes in the data.

predict
(*args, **kwargs)¶ Perform prediction of the given classifier for a batch of inputs, taking an expectation over transformations.
 Parameters
x – Test set.
batch_size – Batch size.
is_abstain (boolean) – True if function will abstain from prediction and return 0s. Default: True
 Returns
Array of predictions of shape (nb_inputs, nb_classes).

save
(filename: str, path: Optional[str] = None) → None¶ Save a model to file in the format specific to the backend framework.
 Parameters
filename (
str
) – Name of the file where to store the model.path – Path of the folder where to store the model. If no path is specified, the model will be stored in the default data location of the library ART_DATA_PATH.

set_learning_phase
(train: bool) → None¶ Set the learning phase for the backend framework.
 Parameters
train (
bool
) – True to set the learning phase to training, False to set it to prediction.

set_params
(**kwargs) → None¶ Take a dictionary of parameters and apply checks before setting them as attributes.
 Parameters
kwargs – A dictionary of attributes.

TensorFlow V2 Randomized Smoothing Classifier¶

class
art.estimators.certification.randomized_smoothing.
TensorFlowV2RandomizedSmoothing
(model, nb_classes: int, input_shape: Tuple[int, …], loss_object: Optional[tf.Tensor] = None, train_step: Optional[Callable] = None, channels_first: bool = False, clip_values: Optional[CLIP_VALUES_TYPE] = None, preprocessing_defences: Optional[Union[Preprocessor, List[Preprocessor]]] = None, postprocessing_defences: Optional[Union[Postprocessor, List[Postprocessor]]] = None, preprocessing: PREPROCESSING_TYPE = (0, 1), sample_size: int = 32, scale: float = 0.1, alpha: float = 0.001)¶ Implementation of Randomized Smoothing applied to classifier predictions and gradients, as introduced in Cohen et al. (2019).
Paper link: https://arxiv.org/abs/1902.02918
__init__
(model, nb_classes: int, input_shape: Tuple[int, …], loss_object: Optional[tf.Tensor] = None, train_step: Optional[Callable] = None, channels_first: bool = False, clip_values: Optional[CLIP_VALUES_TYPE] = None, preprocessing_defences: Optional[Union[Preprocessor, List[Preprocessor]]] = None, postprocessing_defences: Optional[Union[Postprocessor, List[Postprocessor]]] = None, preprocessing: PREPROCESSING_TYPE = (0, 1), sample_size: int = 32, scale: float = 0.1, alpha: float = 0.001)¶ Create a randomized smoothing classifier.
 Parameters
model (function or callable class) – a python functions or callable class defining the model and providing it prediction as output.
nb_classes (
int
) – the number of classes in the classification task.input_shape (
Tuple
) – Shape of one input for the classifier, e.g. for MNIST input_shape=(28, 28, 1).loss_object – The loss function for which to compute gradients. This parameter is applied for training the model and computing gradients of the loss w.r.t. the input.
train_step – A function that applies a gradient update to the trainable variables.
channels_first (
bool
) – Set channels first or last.clip_values – Tuple of the form (min, max) of floats or np.ndarray representing the minimum and maximum values allowed for features. If floats are provided, these will be used as the range of all features. If arrays are provided, each value will be considered the bound for a feature, thus the shape of clip values needs to match the total number of features.
preprocessing_defences – Preprocessing defence(s) to be applied by the classifier.
postprocessing_defences – Postprocessing defence(s) to be applied by the classifier.
preprocessing – Tuple of the form (subtrahend, divisor) of floats or np.ndarray of values to be used for data preprocessing. The first value will be subtracted from the input. The input will then be divided by the second one.
sample_size (
int
) – Number of samples for smoothing.scale (
float
) – Standard deviation of Gaussian noise added.alpha (
float
) – The failure probability of smoothing.

certify
(x: numpy.ndarray, n: int, batch_size: int = 32) → Tuple[numpy.ndarray, numpy.ndarray]¶ Computes certifiable radius around input x and returns radius r and prediction.
 Return type
Tuple
 Parameters
x (
ndarray
) – Sample input with shape as expected by the model.n (
int
) – Number of samples for estimate certifiable radius.batch_size (
int
) – Batch size.
 Returns
Tuple of length 2 of the selected class and certified radius.

property
channel_index
¶  Returns
Index of the axis containing the color channels in the samples x.

property
channels_first
¶  Returns
Boolean to indicate index of the color channels in the sample x.

class_gradient
(*args, **kwargs)¶ Compute perclass derivatives of the given classifier w.r.t. x of original classifier.
 Parameters
x – Sample input with shape as expected by the model.
label – Index of a specific perclass derivative. If an integer is provided, the gradient of that class output is computed for all samples. If multiple values as provided, the first dimension should match the batch size of x, and each value will be used as target for its corresponding sample in x. If None, then gradients for all classes will be computed for each sample.
 Returns
Array of gradients of input features w.r.t. each class in the form (batch_size, nb_classes, input_shape) when computing for all classes, otherwise shape becomes (batch_size, 1, input_shape) when label parameter is specified.

property
clip_values
¶ Return the clip values of the input samples.
 Returns
Clip values (min, max).

fit
(*args, **kwargs)¶ Fit the classifier on the training set (x, y).
 Parameters
x – Training data.
y – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
batch_size – Batch size.
kwargs (dict) – Dictionary of frameworkspecific arguments. This parameter is not currently supported for PyTorch and providing it takes no effect.
 Key nb_epochs
Number of epochs to use for training
 Returns
None

fit_generator
(generator: DataGenerator, nb_epochs: int = 20, **kwargs) → None¶ Fit the classifier using the generator that yields batches as specified.
 Parameters
generator – Batch generator providing (x, y) for each epoch. If the generator can be used for native training in TensorFlow, it will.
nb_epochs (
int
) – Number of epochs to use for training.kwargs – Dictionary of frameworkspecific arguments. This parameter is not currently supported for TensorFlow and providing it takes no effect.

get_activations
(*args, **kwargs)¶ Return the output of the specified layer for input x. layer is specified by layer index (between 0 and nb_layers  1) or by name. The number of layers can be determined by counting the results returned by calling layer_names.
 Parameters
x – Input for computing the activations.
layer – Layer for computing the activations.
batch_size – Batch size.
 Returns
The output of layer, where the first dimension is the batch size corresponding to x.

get_params
() → Dict[str, Any]¶ Get all parameters and their values of this estimator.
 Returns
A dictionary of string parameter names to their value.

property
input_shape
¶ Return the shape of one input sample.
 Returns
Shape of one input sample.

property
layer_names
¶ Return the hidden layers in the model, if applicable.
 Returns
The hidden layers in the model, input and output layers excluded.
Warning
layer_names tries to infer the internal structure of the model. This feature comes with no guarantees on the correctness of the result. The intended order of the layers tries to match their order in the model, but this is not guaranteed either.

property
learning_phase
¶ The learning phase set by the user. Possible values are True for training or False for prediction and None if it has not been set by the library. In the latter case, the library does not do any explicit learning phase manipulation and the current value of the backend framework is used. If a value has been set by the user for this property, it will impact all following computations for model fitting, prediction and gradients.
 Returns
Learning phase.

loss
(x: numpy.ndarray, y: numpy.ndarray, **kwargs) → numpy.ndarray¶ Compute the loss of the neural network for samples x.
 Parameters
x (
ndarray
) – Samples of shape (nb_samples, nb_features) or (nb_samples, nb_pixels_1, nb_pixels_2, nb_channels) or (nb_samples, nb_channels, nb_pixels_1, nb_pixels_2).y (
ndarray
) – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
 Returns
Loss values.
 Return type
Format as expected by the model

loss_gradient
(*args, **kwargs)¶ Compute the gradient of the loss function w.r.t. x.
 Parameters
x – Sample input with shape as expected by the model.
y – Correct labels, onevsrest encoding.
sampling (bool) – True if loss gradients should be determined with Monte Carlo sampling.
 Returns
Array of gradients of the same shape as x.

loss_gradient_framework
(x: tf.Tensor, y: tf.Tensor, **kwargs) → tf.Tensor¶ Compute the gradient of the loss function w.r.t. x.
 Parameters
x – Input with shape as expected by the model.
y – Target values (class labels) onehotencoded of shape (nb_samples, nb_classes) or indices of shape (nb_samples,).
 Returns
Gradients of the same shape as x.

property
model
¶ Return the model.
 Returns
The model.

property
nb_classes
¶ Return the number of output classes.
 Returns
Number of classes in the data.

predict
(*args, **kwargs)¶ Perform prediction of the given classifier for a batch of inputs, taking an expectation over transformations.
 Parameters
x – Test set.
batch_size – Batch size.
is_abstain (boolean) – True if function will abstain from prediction and return 0s. Default: True
 Returns
Array of predictions of shape (nb_inputs, nb_classes).

save
(filename: str, path: Optional[str] = None) → None¶ Save a model to file in the format specific to the backend framework. For TensorFlow, .ckpt is used.
 Parameters
filename (
str
) – Name of the file where to store the model.path – Path of the folder where to store the model. If no path is specified, the model will be stored in the default data location of the library ART_DATA_PATH.

set_learning_phase
(train: bool) → None¶ Set the learning phase for the backend framework.
 Parameters
train (
bool
) – True to set the learning phase to training, False to set it to prediction.

set_params
(**kwargs) → None¶ Take a dictionary of parameters and apply checks before setting them as attributes.
 Parameters
kwargs – A dictionary of attributes.
