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31 changes: 28 additions & 3 deletions tslearn/svm.py
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,29 @@ def _kernel_func_gak(sz, d, gamma):
gamma = 1.
return lambda x, y: cdist_gak(x.reshape((-1, sz, d)), y.reshape((-1, sz, d)), sigma=numpy.sqrt(gamma / 2.))

def _sparse_kernel_func_gak(sz, d, gamma, slice_support_vectors=None):
if gamma == "auto":
gamma = 1.

def sparse_gak(X, X_fit):

if X_fit is X:
return cdist_gak(X.reshape((-1, sz, d)), None, sigma=numpy.sqrt(gamma / 2.))

if slice_support_vectors is not None:
# slice out support vectors
sliced_X_fit = X_fit[slice_support_vectors]
gak_sim_dense = cdist_gak(X.reshape((-1, sz, d)), sliced_X_fit.reshape((-1, sz, d)), sigma=numpy.sqrt(gamma / 2.))

# act like nothing has happend ...
gak_sim = numpy.empty((len(X), len(X_fit)))
gak_sim[:, slice_support_vectors] = gak_sim_dense

return gak_sim

return cdist_gak(X.reshape((-1, sz, d)), X_fit.reshape((-1, sz, d)), sigma=numpy.sqrt(gamma / 2.))

return sparse_gak

class TimeSeriesSVC(BaseSVC):
"""Time-series specific Support Vector Classifier.
Expand Down Expand Up @@ -148,7 +171,7 @@ def __init__(self, sz, d, C=1.0, kernel="gak", degree=3, gamma="auto", coef0=0.0
self.sz = sz
self.d = d
if kernel == "gak":
kernel = _kernel_func_gak(sz=sz, d=d, gamma=gamma)
kernel = _sparse_kernel_func_gak(sz=sz, d=d, gamma=gamma)
super(TimeSeriesSVC, self).__init__(C=C, kernel=kernel, degree=degree, gamma=gamma, coef0=coef0,
shrinking=shrinking, probability=probability, tol=tol,
cache_size=cache_size, class_weight=class_weight, verbose=verbose,
Expand All @@ -169,8 +192,10 @@ def fit(self, X, y, sample_weight=None):
sklearn_X = _prepare_ts_datasets_sklearn(X)
if self.kernel == "gak" and self.gamma == "auto":
self.gamma = gamma_soft_dtw(to_time_series_dataset(X))
self.kernel = _kernel_func_gak(sz=self.sz, d=self.d, gamma=self.gamma)
return super(TimeSeriesSVC, self).fit(sklearn_X, y, sample_weight=sample_weight)
self.kernel = _sparse_kernel_func_gak(sz=self.sz, d=self.d, gamma=self.gamma)
super(TimeSeriesSVC, self).fit(sklearn_X, y, sample_weight=sample_weight)
self.kernel = _sparse_kernel_func_gak(sz=self.sz, d=self.d, gamma=self.gamma, slice_support_vectors=self.support_)
return self

def predict(self, X):
sklearn_X = _prepare_ts_datasets_sklearn(X)
Expand Down