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Classifier

CNNClassifier

Time Convolutional Neural Network (CNN), as described in [1].

Zhao et al. 2017 uses sigmoid activation in the hidden layers. To obtain same behaviour as Zhao et al. 2017, set activation_hidden to “sigmoid”.

Adapted from the implementation from Fawaz et. al https://github.com/hfawaz/dl-4-tsc/blob/master/classifiers/cnn.py

Quickstart

python
from sktime.classification.deep_learning.cnn import CNNClassifier

estimator = CNNClassifier(n_epochs=2000, batch_size=16, kernel_size=7, avg_pool_size=3, n_conv_layers=2, callbacks=None, verbose=False, loss='categorical_crossentropy', metrics=None, random_state=None, activation='softmax', activation_hidden='changing_from_sigmoid_to_relu_in_0.42.0', use_bias=True, optimizer=None, filter_sizes=None, padding='auto')

Parameters(16)

n_epochsint, default = 2000
the number of epochs to train the model
batch_sizeint, default = 16
the number of samples per gradient update.
kernel_sizeint, default = 7
the length of the 1D convolution window
avg_pool_sizeint, default = 3
size of the average pooling windows
n_conv_layersint, default = 2
the number of convolutional plus average pooling layers
callbackslist of keras.callbacks, default = None
verboseboolean, default = False
whether to output extra information
lossstring, default=”categorical_crossentropy”
fit parameter for the keras model
metricslist of strings, default=[“accuracy”],
random_stateint or None, default=None
Seed for random number generation.
activationstring or a tf callable, default=”softmax”

Activation function used in the output layer. List of available activation functions: https://keras.io/api/layers/activations/

activation_hiddenstring or a tf callable, default=”sigmoid”

Activation function used in the hidden layers. List of available activation functions: https://keras.io/api/layers/activations/ Default value of activation_hidden will change to “relu” in version ‘0.42.0’.

use_biasboolean, default = True
whether the layer uses a bias vector.
optimizerkeras.optimizers object, default = Adam(lr=0.01)
specify the optimizer and the learning rate to be used.
filter_sizesarray of shape (n_conv_layers) default = [6, 12]
paddingstring, default = “auto”

Controls padding logic for the convolutional layers, i.e. whether 'valid' and 'same' are passed to the Conv1D layer. - “auto”: as per original implementation, "same" is passed if

input_shape[0] < 60 in the input layer, and "valid" otherwise.

  • “valid”, “same”, and other values are passed directly to Conv1D

Examples

>>> from sktime.classification.deep_learning.cnn import CNNClassifier
>>> from sktime.datasets import load_unit_test
>>> X_train, y_train = load_unit_test (split = "train")
>>> X_test, y_test = load_unit_test (split = "test")
>>> cnn = CNNClassifier (n_epochs = 20, batch_size = 4)
>>> cnn. fit (X_train, y_train) CNNClassifier(
... )

References

[1]

Zhao et. al, Convolutional neural networks for time series classification,

Journal of Systems Engineering and Electronics, 28(1):2017.