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tapnet.py
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tapnet.py
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"""Time Convolutional Neural Network (CNN) for classification."""
__author__ = ["jnrusson1"]
__all__ = ["TapNetRegressor"]
from copy import deepcopy
from sklearn.utils import check_random_state
from sktime.networks.tapnet import TapNetNetwork
from sktime.regression.deep_learning.base import BaseDeepRegressor
from sktime.utils.validation._dependencies import _check_dl_dependencies
class TapNetRegressor(BaseDeepRegressor):
"""Time series attentional prototype network (TapNet), as described in [1].
TapNet was initially proposed for multivariate time series
classification. The is an adaptation for time series regression. TapNet comprises
these components: random dimension permutation, multivariate time series
encoding, and attentional prototype learning.
Parameters
----------
filter_sizes : array of int, default = (256, 256, 128)
sets the kernel size argument for each convolutional block.
Controls number of convolutional filters
and number of neurons in attention dense layers.
kernel_size : array of int, default = (8, 5, 3)
controls the size of the convolutional kernels
layers : array of int, default = (500, 300)
size of dense layers
n_epochs : int, default = 2000
number of epochs to train the model
batch_size : int, default = 16
number of samples per update
dropout : float, default = 0.5
dropout rate, in the range [0, 1)
dilation : int, default = 1
dilation value
activation : str, default = "sigmoid"
activation function for the last output layer
loss : str, default = "mean_squared_error"
loss function for the classifier
optimizer : str or None, default = "Adam(lr=0.01)"
gradient updating function for the classifier
use_bias : bool, default = True
whether to use bias in the output dense layer
use_rp : bool, default = True
whether to use random projections
use_att : bool, default = True
whether to use self attention
use_lstm : bool, default = True
whether to use an LSTM layer
use_cnn : bool, default = True
whether to use a CNN layer
verbose : bool, default = False
whether to output extra information
random_state : int or None, default = None
seed for random
References
----------
.. [1] Zhang et al. Tapnet: Multivariate time series classification with
attentional prototypical network,
Proceedings of the AAAI Conference on Artificial Intelligence
34(4), 6845-6852, 2020
Notes
-----
The Implementation of TapNet found at https://github.com/kdd2019-tapnet/tapnet
Currently does not implement custom distance matrix loss function
or class based self attention.
"""
_tags = {
# packaging info
# --------------
"authors": ["jnrusson1"],
"maintainers": ["jnrusson1"],
"python_dependencies": "tensorflow",
# estimator type handled by parent class
}
def __init__(
self,
n_epochs=2000,
batch_size=16,
dropout=0.5,
filter_sizes=(256, 256, 128),
kernel_size=(8, 5, 3),
dilation=1,
layers=(500, 300),
use_rp=True,
activation=None,
rp_params=(-1, 3),
use_bias=True,
use_att=True,
use_lstm=True,
use_cnn=True,
random_state=None,
padding="same",
loss="mean_squared_error",
optimizer=None,
metrics=None,
callbacks=None,
verbose=False,
):
_check_dl_dependencies(severity="error")
self.batch_size = batch_size
self.random_state = random_state
self.kernel_size = kernel_size
self.layers = layers
self.rp_params = rp_params
self.filter_sizes = filter_sizes
self.activation = activation
self.use_att = use_att
self.use_bias = use_bias
self.dilation = dilation
self.padding = padding
self.n_epochs = n_epochs
self.loss = loss
self.optimizer = optimizer
self.metrics = metrics
self.callbacks = callbacks
self.verbose = verbose
self.dropout = dropout
self.use_lstm = use_lstm
self.use_cnn = use_cnn
# parameters for random projection
self.use_rp = use_rp
self.rp_params = rp_params
super().__init__()
self._network = TapNetNetwork(
dropout=self.dropout,
filter_sizes=self.filter_sizes,
kernel_size=self.kernel_size,
dilation=self.dilation,
layers=self.layers,
use_rp=self.use_rp,
rp_params=self.rp_params,
use_att=self.use_att,
use_lstm=self.use_lstm,
use_cnn=self.use_cnn,
random_state=self.random_state,
padding=self.padding,
)
def build_model(self, input_shape, **kwargs):
"""Construct a complied, un-trained, keras model that is ready for training.
In sktime, time series are stored in numpy arrays of shape (d,m), where d
is the number of dimensions, m is the series length. Keras/tensorflow assume
data is in shape (m,d). This method also assumes (m,d). Transpose should
happen in fit.
Parameters
----------
input_shape : tuple
The shape of the data fed into the input layer, should be (m, d)
Returns
-------
output: a compiled Keras model
"""
import tensorflow as tf
from tensorflow import keras
tf.random.set_seed(self.random_state)
metrics = ["mean_squared_error"] if self.metrics is None else self.metrics
input_layer, output_layer = self._network.build_network(input_shape, **kwargs)
output_layer = keras.layers.Dense(
units=1, activation=self.activation, use_bias=self.use_bias
)(output_layer)
self.optimizer_ = (
keras.optimizers.Adam(learning_rate=0.01)
if self.optimizer is None
else self.optimizer
)
model = keras.models.Model(inputs=input_layer, outputs=output_layer)
model.compile(
loss=self.loss,
optimizer=self.optimizer_,
metrics=metrics,
)
return model
def _fit(self, X, y):
"""Fit the regressor on the training set (X, y).
Parameters
----------
X : np.ndarray of shape = (n_instances(n), n_dimensions(d), series_length(m))
Input training samples
y : np.ndarray of shape n
Input training responses
Returns
-------
self: object
"""
# Transpose to conform to expectation format from keras
X = X.transpose(0, 2, 1)
check_random_state(self.random_state)
self.input_shape = X.shape[1:]
self.model_ = self.build_model(self.input_shape)
if self.verbose:
self.model_.summary()
self.history = self.model_.fit(
X,
y,
batch_size=self.batch_size,
epochs=self.n_epochs,
verbose=self.verbose,
callbacks=deepcopy(self.callbacks) if self.callbacks else [],
)
return self
@classmethod
def get_test_params(cls, parameter_set="default"):
"""Return testing parameter settings for the estimator.
Parameters
----------
parameter_set : str, default="default"
Name of the set of test parameters to return, for use in tests. If no
special parameters are defined for a value, will return ``"default"`` set.
For classifiers, a "default" set of parameters should be provided for
general testing, and a "results_comparison" set for comparing against
previously recorded results if the general set does not produce suitable
probabilities to compare against.
Returns
-------
params : dict or list of dict, default={}
Parameters to create testing instances of the class.
Each dict are parameters to construct an "interesting" test instance, i.e.,
``MyClass(**params)`` or ``MyClass(**params[i])`` creates a valid test
instance.
``create_test_instance`` uses the first (or only) dictionary in ``params``.
"""
from sktime.utils.validation._dependencies import _check_soft_dependencies
param1 = {
"n_epochs": 10,
"batch_size": 4,
"padding": "valid",
"filter_sizes": (16, 16, 16),
"kernel_size": (3, 3, 1),
"layers": (25, 50),
}
param2 = {
"n_epochs": 20,
"use_cnn": False,
"layers": (25, 25),
}
test_params = [param1, param2]
if _check_soft_dependencies("keras", severity="none"):
from keras.callbacks import LambdaCallback
test_params.append(
{
"n_epochs": 2,
"callbacks": [LambdaCallback()],
}
)
return test_params