BaseNeuralDetector
- class dtaianomaly.anomaly_detection.BaseNeuralDetector(supervision: Supervision, window_size: int | Literal['fft', 'acf', 'mwf', 'suss'], stride: int = 1, standard_scaling: bool = True, batch_size: int = 32, data_loader_kwargs: dict[str, any] = None, optimizer: Literal['adam', 'sgd'] = 'adam', learning_rate: float = 0.001, compile_model: bool = False, compile_mode: Literal['default', 'reduce-overhead', 'max-autotune', 'max-autotune-no-cudagraphs'] = 'default', n_epochs: int = 10, loss_function: Literal['mse', 'l1', 'huber'] = 'mse', device: str = 'cpu', seed: int = None)[source]
Base class for neural anomaly detectors, based on PyTorch.
This class implements the main functionality for training a model and detecting anomalies, including building the data loader, building the optimizer, and implementing the main train and evaluation loops. Extensions of this class should also implement methods to build the data set, the neural architecture, and how to train and evaluate on a single batch.
- Parameters:
- supervisionSupervision
The type of supervision this anomaly detector requires.
- window_sizeint or str
The window size to use for extracting sliding windows from the time series. This value will be passed to
compute_window_size().- strideint, default=1
The stride, i.e., the step size for extracting sliding windows from the time series.
- standard_scalingbool, default=True
Whether to standard scale each window independently, before feeding it to the network.
- batch_sizeint, default=32
The size of the batches to feed to the network.
- data_loader_kwargsdictionary, default=None
Additional kwargs to be passed to the data loader. For more information, see: https://docs.pytorch.org/docs/stable/data.html.
- optimizer{“adam”, “sgd”} or callable default=”adam”
The optimizer to use for learning the weights. If “adam” is given, then the torch.optim.Adam optimizer will be used. If “sgd” is given, then the torch.optim.SGD optimizer will be used. Otherwise, a callable should be given, which takes as input the network parameters, and then creates an optimizer.
- learning_ratefloat, default=1e-3
The learning rate to use for training the network. Has no effect if optimize is a callable.
- compile_modelbool, default=False
Whether the network architecture should be compiled or not before training the weights. For more information, see: https://docs.pytorch.org/docs/stable/generated/torch.compile.html.
- compile_mode{“default”, “reduce-overhead”, “max-autotune”, “max-autotune-no-cudagraphs”}, default=”default”
Method to compile the architecture. For more information, see: https://docs.pytorch.org/docs/stable/generated/torch.compile.html.
- n_epochsint, default=10
The number of epochs for which the neural network should be trained.
- loss_function{“mse”, “l1”, “huber} or torch.nn.Module, default=”mse”
The loss function to use for updating the weights. Valid options are:
'mse': Use the Mean Squared Error loss.'l1': Use the L1-loss or the mean absolute error.'huber': Use the huber loss, which smoothly combines the MSE-loss with the L1-loss.torch.nn.Module: a custom torch module to use for the loss function.
- devicestr, default=”cpu”
The device on which te neural network should be trained. For more information, see: https://docs.pytorch.org/docs/stable/tensor_attributes.html#torch-device.
- seedint, default=None
The seed used for training the model. This seed will update the torch and numpy seed at the beginning of the fit method.
- Attributes:
- window_size_int
The effectively used window size for this anomaly detector.
- optimizer_torch.optim.Optimizer
The optimizer used for learning the weights of the network.
- neural_network_torch.nn.Module
The PyTorch network architecture.
See also
BaseNeuralForecastingDetectorUse a neural network to forecast the time series, and detect anomalies by measuring the difference with the actual observations.
BaseNeuralReconstructionDetectorUse a neural network to reconstruct windows in the time series, and detect anomalies as windows that are incorrectly reconstructed.
- check_is_fitted() None
Raise an error if this object is not fitted.
Check whether this object is fitted, and if it is not fitted, an exception is thrown.
- Raises:
- NotFittedError
If this object is not fitted.
- decision_function(X: ndarray) array
Compute anomaly scores.
Compute the anomaly scores for the given time series using this detector.
- Parameters:
- Xarray-like of shape (n_samples, n_attributes)
Input time series.
- Returns:
- array-like of shape (n_samples)
The computed anomaly scores.
- fit(X: ndarray, y: ndarray = None, **kwargs) BaseDetector
Fit this detector.
Fit this detector to the given data.
- Parameters:
- Xarray-like of shape (n_samples, n_attributes)
Input time series.
- yarray-like, default=None
Ground-truth information.
- **kwargs
Additional parameters to be used to fit the anomaly detector.
- Returns:
- BaseDetector
Returns the instance itself.
- is_fitted() bool
Check whether this object is fitted.
Check whether all the attributes of this object that end with an underscore (‘_’) has been initialized.
- Returns:
- bool
True if and only if all the attributes of this object ending with ‘_’ are initialized.
- predict_confidence(X: ndarray, X_train: ndarray = None, contamination: float = 0.05, decision_scores_given: bool = False)
Predict the confidence of the anomaly scores on the test given test data [26].
This method implements ExCeeD (Example-wise Confidence of anomaly Detectors) to estimate the confidence. ExCeed transforms the predicted decision scores to probability estimates using a Bayesian approach, which enables to assign a confidence score to each prediction which captures the uncertainty of the anomaly detector in that prediction.
- Parameters:
- Xarray-like of shape (n_samples, n_attributes)
The test time series for which the confidence of anomaly scores should be predicted.
- X_trainarray-like of shape (n_samples_train, n_attributes), default=None
The training time series, which can be used as reference. If
X_train=None, the test set is used as reference set.- contaminationfloat, default=0.05
The (estimated) contamination rate for the data, i.e., the expected percentage of anomalies.
- decision_scores_givenbool, default=False
Whether the given
XandX_trainrepresent time series data or decision scores. Ifdecision_scores_given=False(default), then the given arrays are interpreted as time series. Otherwise, they are interpreted as decision scores, as computed bydecision_function().
- Returns:
- array-like of shape (n_samples)
The confidence of this anomaly detector in each prediction in the given test time series.
- predict_proba(X: ndarray) ndarray
Predict anomaly probabilities.
Estimate the probability of a sample of X being anomalous, based on the anomaly scores obtained from decision_function by rescaling them to the range of [0, 1] via min-max scaling.
- Parameters:
- Xarray-like of shape (n_samples, n_attributes)
Input time series.
- Returns:
- array-like of shape (n_samples)
1D array with the same length as X, with values in the interval [0, 1], in which a higher value implies that the instance is more likely to be anomalous.
- Raises:
- ValueError
If scores is not a valid array.
- ValueError
If the prediction scores from ‘decision_function’ are constant, but not in the interval [0, 1], because these values can not unambiguously be transformed to an anomaly probability.
- requires_fitting() bool
Check whether this object requires fitting.
Check whether any of the attributes of this object ends with an underscore (‘_’), which indicates that the attribute is set when the object is fitted. Note that this method does not check whether the object is fitted, i.e., whether the attributes have been set.
- Returns:
- bool
True if and only if this object has attributes that end with ‘_’.
- save(path: str | Path) None
Save this detector.
Save detector to disk as a pickle file with extension .dtai. If the given path consists of multiple subdirectories, then the not existing subdirectories are created.
- Parameters:
- pathstr or Path
Location where to store the detector.