Source code for alibi_detect.cd.classifier

import numpy as np
from typing import Callable, Dict, Optional, Union
from alibi_detect.utils.frameworks import has_pytorch, has_tensorflow

if has_pytorch:
    from torch.utils.data import DataLoader
    from alibi_detect.cd.pytorch.classifier import ClassifierDriftTorch
    from alibi_detect.utils.pytorch.data import TorchDataset

if has_tensorflow:
    from alibi_detect.cd.tensorflow.classifier import ClassifierDriftTF
    from alibi_detect.utils.tensorflow.data import TFDataset


[docs]class ClassifierDrift:
[docs] def __init__( self, x_ref: Union[np.ndarray, list], model: Callable, backend: str = 'tensorflow', p_val: float = .05, preprocess_x_ref: bool = True, update_x_ref: Optional[Dict[str, int]] = None, preprocess_fn: Optional[Callable] = None, preds_type: str = 'probs', binarize_preds: bool = False, reg_loss_fn: Callable = (lambda model: 0), train_size: Optional[float] = .75, n_folds: Optional[int] = None, retrain_from_scratch: bool = True, seed: int = 0, optimizer: Optional[Callable] = None, learning_rate: float = 1e-3, batch_size: int = 32, preprocess_batch_fn: Optional[Callable] = None, epochs: int = 3, verbose: int = 0, train_kwargs: Optional[dict] = None, device: Optional[str] = None, dataset: Optional[Callable] = None, dataloader: Optional[Callable] = None, data_type: Optional[str] = None ) -> None: """ Classifier-based drift detector. The classifier is trained on a fraction of the combined reference and test data and drift is detected on the remaining data. To use all the data to detect drift, a stratified cross-validation scheme can be chosen. Parameters ---------- x_ref Data used as reference distribution. model PyTorch or TensorFlow classification model used for drift detection. backend Backend used for the training loop implementation. p_val p-value used for the significance of the test. preprocess_x_ref Whether to already preprocess and store the reference data. update_x_ref Reference data can optionally be updated to the last n instances seen by the detector or via reservoir sampling with size n. For the former, the parameter equals {'last': n} while for reservoir sampling {'reservoir_sampling': n} is passed. preprocess_fn Function to preprocess the data before computing the data drift metrics. preds_type Whether the model outputs 'probs' or 'logits' binarize_preds Whether to test for discrepency on soft (e.g. probs/logits) model predictions directly with a K-S test or binarise to 0-1 prediction errors and apply a binomial test. reg_loss_fn The regularisation term reg_loss_fn(model) is added to the loss function being optimized. train_size Optional fraction (float between 0 and 1) of the dataset used to train the classifier. The drift is detected on `1 - train_size`. Cannot be used in combination with `n_folds`. n_folds Optional number of stratified folds used for training. The model preds are then calculated on all the out-of-fold instances. This allows to leverage all the reference and test data for drift detection at the expense of longer computation. If both `train_size` and `n_folds` are specified, `n_folds` is prioritized. retrain_from_scratch Whether the classifier should be retrained from scratch for each set of test data or whether it should instead continue training from where it left off on the previous set. seed Optional random seed for fold selection. optimizer Optimizer used during training of the classifier. learning_rate Learning rate used by optimizer. batch_size Batch size used during training of the classifier. preprocess_batch_fn Optional batch preprocessing function. For example to convert a list of objects to a batch which can be processed by the model. epochs Number of training epochs for the classifier for each (optional) fold. verbose Verbosity level during the training of the classifier. 0 is silent, 1 a progress bar. train_kwargs Optional additional kwargs when fitting the classifier. device Device type used. The default None tries to use the GPU and falls back on CPU if needed. Can be specified by passing either 'cuda', 'gpu' or 'cpu'. Only relevant for 'pytorch' backend. dataset Dataset object used during training. dataloader Dataloader object used during training. Only relevant for 'pytorch' backend. data_type Optionally specify the data type (tabular, image or time-series). Added to metadata. """ super().__init__() backend = backend.lower() if backend == 'tensorflow' and not has_tensorflow or backend == 'pytorch' and not has_pytorch: raise ImportError(f'{backend} not installed. Cannot initialize and run the ' f'ClassifierDrift detector with {backend} backend.') elif backend not in ['tensorflow', 'pytorch']: raise NotImplementedError(f'{backend} not implemented. Use tensorflow or pytorch instead.') kwargs = locals() args = [kwargs['x_ref'], kwargs['model']] pop_kwargs = ['self', 'x_ref', 'model', 'backend', '__class__'] if kwargs['optimizer'] is None: pop_kwargs += ['optimizer'] [kwargs.pop(k, None) for k in pop_kwargs] if backend == 'tensorflow' and has_tensorflow: pop_kwargs = ['device', 'dataloader'] [kwargs.pop(k, None) for k in pop_kwargs] if dataset is None: kwargs.update({'dataset': TFDataset}) self._detector = ClassifierDriftTF(*args, **kwargs) # type: ignore else: if dataset is None: kwargs.update({'dataset': TorchDataset}) if dataloader is None: kwargs.update({'dataloader': DataLoader}) self._detector = ClassifierDriftTorch(*args, **kwargs) # type: ignore self.meta = self._detector.meta
[docs] def predict(self, x: Union[np.ndarray, list], return_p_val: bool = True, return_distance: bool = True, return_probs: bool = True, return_model: bool = True) \ -> Dict[str, Dict[str, Union[str, int, float, Callable]]]: """ Predict whether a batch of data has drifted from the reference data. Parameters ---------- x Batch of instances. return_p_val Whether to return the p-value of the test. return_distance Whether to return a notion of strength of the drift. K-S test stat if binarize_preds=False, otherwise relative error reduction. return_probs Whether to return the instance level classifier probabilities for the reference and test data (0=reference data, 1=test data). return_model Whether to return the updated model trained to discriminate reference and test instances. Returns ------- Dictionary containing 'meta' and 'data' dictionaries. 'meta' has the model's metadata. 'data' contains the drift prediction and optionally the p-value, performance of the classifier relative to its expectation under the no-change null, the out-of-fold classifier model prediction probabilities on the reference and test data, and the trained model. """ return self._detector.predict(x, return_p_val, return_distance, return_probs, return_model)