def score(self, X, y, sample_weight=None):
"""
Returns the mean accuracy on the given test data and labels.
Parameters
----------
X : array, shape (n_samples, n_features)
Test samples.
y : array, shape (n_samples,)
True labels for X.
sample_weight : array, shape (n_samples,), optional
Sample weights.
Returns
-------
score : float
Mean accuracy of self.predict(X) w.r.t. y.
"""
# Check input arrays
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
y = check_array(y.astype(int), ndim=1, dtype='numeric',
force_all_finite=True)
# Check input arrays are same length
if X.shape[0] != y.size:
raise ValueError("Number of samples in X and y must be the same: "
"{} vs {}".format(X.shape[0], y.size))
return accuracy_score(y, self.predict(X), sample_weight=sample_weight)
def transform(self, X, Y=None):
"""
Apply the dimension reduction learned on the train data.
Parameters
----------
X : array, shape (n_samples, n_features)
Input X data.
Y : array, shape (n_samples, n_targets) or None (default=None)
Input Y data. If Y=None, then only the transformed X data are
returned.
Returns
-------
X_new : array, shape (n_samples, n_components)
Transformed X data.
Y_new : array, shape (n_samples, n_components)
Transformed Y data. If Y=None, only X_new is returned.
"""
self._check_is_fitted()
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
if Y is None:
return self.cca.transform(X, Y=None, copy=True)
else:
Y = check_array(Y, ndim=2, dtype='numeric', force_all_finite=True)
X_new, Y_new = self.cca.transform(X, Y=Y, copy=True)
# If n_components=1, reshape Y_new so it is 2D
if self.n_components_ == 1:
n_samples = Y_new.shape[0]
Y_new = Y_new.reshape((n_samples, 1))
return X_new, Y_new
def inverse_transform(self, X, Y=None):
"""
Transform data back to its original space.
Note: This is not exact!
Parameters
----------
X : array, shape (n_samples, n_components)
Transformed X data.
Y : array, shape (n_samples, n_components) or None (default=None)
Transformed Y data. If Y=None, only the X data are transformed back
to the original space.
Returns
-------
X_original : array, shape (n_samples, n_features)
X data transformed back into original space.
Y_original : array, shape (n_samples, n_targets)
Y data transformed back into original space. If Y=None, only
X_original is returned.
"""
self._check_is_fitted()
# Check X is in transformed space
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
if X.shape[1] != self.n_components_:
raise ValueError("X has {} features per sample."
"Expecting {}".format(X.shape[1],
self.n_components_))
# Invert X into original space
X_original = np.dot(X, self.components_) + self.mean_
if Y is None:
return X_original
else:
# Check Y is in transformed space
Y = check_array(Y, ndim=2, dtype='numeric', force_all_finite=True)
if Y.shape[1] != self.n_components_:
raise ValueError("Y has {} features per sample."
"Expecting {}".format(Y.shape[1],
self.n_components_))
# Invert Y into original space
Y_original = np.dot(Y, self.components_y_) + self.mean_y_
return X_original, Y_original
def fit(self, X, y):
"""
Fit PLDA model according to the given training data and parameters.
Parameters
----------
X : array, shape (n_samples, n_features)
Training data.
y : array, shape (n_samples,)
Target values.
"""
# Check input arrays
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
y = check_array(y.astype(int), ndim=1, dtype='numeric',
force_all_finite=True)
# Check input arrays are same length
if X.shape[0] != y.size:
raise ValueError("Number of samples in X and y must be the same: "
"{} vs {}".format(X.shape[0], y.size))
# Check that n_components does not exceed maximum possible
max_components = min(X.shape)
if self.n_components_ is None:
self.n_components_ = max_components
elif self.n_components_ > max_components:
self.n_components_ = max_components
warnings.warn("n_components exceeds maximum possible components. "
"Setting n_components = {}".format(max_components))
# Set useful data attributes
self.classes_ = np.unique(y)
self.mean_ = X.mean(axis=0)
self.class_means_ = self._class_means(X, y)
self._solve_eigen(X, y)
# Adjust coefficients and intercept for binary classification problems
if self.classes_.size == 2:
self.coef_ = np.array(self.coef_[1,:] - self.coef_[0,:], ndmin=2)
self.intercept_ = np.array(self.intercept_[1]-self.intercept_[0],
ndmin=1)
# Transform data so we can get the explained variance
self.explained_variance_ = np.dot(X, self.components_.T).var(axis=0)
self.is_fitted = True
return
def decision_function(self, X):
"""
Predict confidence scores for samples.
The confidence score for a sample is the signed distance of that
sample to the hyperplane.
Parameters
----------
X : array, shape (n_samples, n_features)
Input data.
Returns
-------
scores : array, shape=(n_samples,) if n_classes == 2
else (n_samples, n_classes)
Confidence scores per (sample, class) combination. In the binary
case, confidence score for self.classes_[1] where >0 means this
class would be predicted.
"""
self._check_is_fitted()
# Check input array
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
# Check number of features is correct
n_feat = self.components_.shape[1]
if X.shape[1] != n_feat:
raise ValueError("X has {} features per sample."
"Expecting {}".format(X.shape[1], n_feat))
scores = np.dot(X, self.coef_.T) + self.intercept_
return scores.ravel() if scores.shape[1] == 1 else scores
def inverse_transform(self, X):
"""
Transform data back to its original space.
Note: If n_components is less than the maximum, information will be
lost, so reconstructed data will not exactly match the original data.
Parameters
----------
X : array shape (n_samples, n_components)
New data.
Returns
-------
X_original : array, shape (n_samples, n_features)
Data transformed back into original space.
"""
self._check_is_fitted()
X = check_array(X, ndim=2)
# Check data dimensions
if X.shape[1] != self.n_components_:
raise ValueError("X has {} features per sample."
"Expecting {}".format(X.shape[1],
self.n_components_))
# Inverse transform
X_original = self.mean_ + np.dot(X, self.components_)
return X_original
def transform(self, X):
"""
Transform data.
Parameters
----------
X : array, shape (n_samples, n_features)
Input data.
Returns
-------
X_new : array, shape (n_samples, n_components)
Transformed data.
"""
self._check_is_fitted()
# Check input arrays
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
# Check number of features is correct
n_feat = self.components_.shape[1]
if X.shape[1] != n_feat:
raise ValueError("X has {} features per sample."
"Expecting {}".format(X.shape[1], n_feat))
# Transform data
X_new = np.dot(X, self.components_.T)
return X_new[:,:self.n_components_]
def fit(self, X, Y):
"""
Fit model to data.
Parameters
----------
X : array, shape (n_samples, n_features)
Training vectors, where n_samples is the number of samples and
n_features is the number of predictors.
Y : array, shape (n_samples, n_targets)
Target vectors, where n_samples is the number of samples and
n_targets is the number of response variables.
"""
X = check_array(X, ndim=2, dtype='numeric', force_all_finite=True)
Y = check_array(Y, ndim=2, dtype='numeric', force_all_finite=True)
if X.shape[0] != Y.shape[0]:
raise ValueError("Number of samples in X and Y must be the same: "
"{} vs {}".format(X.shape[0], Y.shape[0]))
if self.n_components_ > X.shape[1]:
raise ValueError("n_components exceeds number of features in X: "
"{} > {}".format(self.n_components_, X.shape[1]))
if self.n_components_ > Y.shape[1]:
raise ValueError("n_components exceeds number of targets in Y: "
"{} > {}".format(self.n_components_, Y.shape[1]))
self.cca.fit(X, Y)
self.components_ = self.cca.x_weights_.T
self.components_y_ = self.cca.y_weights_.T
self.mean_ = self.cca.x_mean_
self.mean_y_ = self.cca.y_mean_
# Get the explained variance of the transformed data
self.explained_variance_ = self.cca.x_scores_.var(axis=0)
self.explained_variance_y_ = self.cca.y_scores_.var(axis=0)
self.is_fitted = True
return
def predict_transformed(self, X_trans):
"""
Predict class labels for data that have already been transformed by
self.transform(X).
This is useful for plotting classification boundaries.
Note: Due to arithemtic discrepancies, this may return slightly
different class labels to self.predict(X).
Parameters
----------
X_trans : array, shape (n_samples, n_components)
Test samples that have already been transformed into PLDA space.
Returns
-------
y : array, shape (n_samples,)
Predicted class labels for X_trans.
"""
self._check_is_fitted()
# Check input array
X_trans = check_array(X_trans, ndim=2)
# Make sure this is a set of transformed data
if X_trans.shape[1] != self.n_components_:
raise ValueError("Number of features in X_trans must match "
"n_components: {}".format(self.n_components_))
# Transform class means into PLDA space
mean_trans = self.transform(self.class_means_)
# Initialize useful values
n_samples = X_trans.shape[0]
n_classes = mean_trans.shape[0]
dists = np.zeros((n_samples,n_classes))
# Compute the distance between each data sample and each class mean
for i,mean in enumerate(mean_trans):
dists[:,i] = np.linalg.norm(X_trans-np.tile(mean,(n_samples,1)),
axis=1)
# Classification based on shortest distance to class mean
ind = dists.argmin(axis=1)
return self.classes_[ind]
