Scalers#

Classes to scale data.

Some of these classes are called internally by other modules, but they can also be used independently as a pre-processing stage.

Scalers can fit to one set of data, and used to transform other data sets with the same number of dimensions.

Examples

Fitting scaler implicitly during transform

>>> # Define some 1D sample data
>>> X = np.random.RandomState(0).normal(2,0.5,200)
>>> (X.mean(),X.std())
>>> (2.0354552465705806, 0.5107113843479977)
>>>
>>> # Scale to zero mean and unit variance
>>> X = eq.scalers.scaler_meanvar().transform(X)
>>> (X.mean(),X.std())
>>> (2.886579864025407e-17, 1.0)

Using the same scaling to transform train and test data

>>> # Define some 5D example data
>>> X = np.random.RandomState(0).uniform(-10,10,size=(50,5))
>>> y = X[:,0]**2 - X[:,4]
>>> # Split into train/test
>>> X_train, X_test,y_train,y_test = eq.datasets.train_test_split(X,y,train=0.7,random_seed=0)
>>> (X_train.min(),X_train.max())
>>> (-9.906090476149059, 9.767476761184525)
>>>
>>> # Define a scaler and fit to training split
>>> scaler = eq.scalers.scaler_minmax()
>>> scaler.fit(X_train)
>>>
>>> # Transform train and test data with same scaler
>>> X_train = scaler.transform(X_train)
>>> X_test = scaler.transform(X_test)
>>> (X_train.min(),X_train.max())
>>> (-1.0, 1.0)
>>>
>>> # Finally, e.g. of transforming data back again
>>> X_train = scaler.untransform(X_train)
>>> (X_train.min(),X_train.max())
>>> (-9.906090476149059, 9.767476761184525)

class equadratures.scalers.scaler_custom(offset, div)[source]#

Scale the data by the provided offset and divisor.

Parameters

offset (float, numpy.ndarray) – Offset to subtract from data. Either a float, or array with shape (number_of_samples, number_of_dimensions).
div (float, numpy.ndarray) – Divisor to divide data with. Either a float, or array with shape (number_of_samples, number_of_dimensions).

transform(X)[source]#

Transforms data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to transform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing transformed data.
Return type: numpy.ndarray

untransform(X)[source]#

Untransforms data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to untransform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing untransformed data.
Return type: numpy.ndarray

class equadratures.scalers.scaler_meanvar[source]#

Scale the data to have a mean of 0 and variance of 1.

fit(X)[source]#

Fit scaler to data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to fit scaler to.

transform(X)[source]#

Transforms data. Calls fit() fit internally if scaler not already fitted.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to transform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing transformed data.
Return type: numpy.ndarray

untransform(X)[source]#

Untransforms data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to untransform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing untransformed data.
Return type: numpy.ndarray
Raises: Exception – scaler has not been fitted

class equadratures.scalers.scaler_minmax[source]#

Scale the data to have a min/max of -1 to 1.

fit(X)[source]#

Fit scaler to data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to fit scaler to.

transform(X)[source]#

Transforms data. Calls fit() fit internally if scaler not already fitted.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to transform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing transformed data.
Return type: numpy.ndarray

untransform(X)[source]#

Untransforms data.

Parameters: X (numpy.ndarray) – Array with shape (number_of_samples, number_of_dimensions) containing data to untransform.
Returns: Array with shape (number_of_samples, number_of_dimensions) containing untransformed data.
Return type: numpy.ndarray
Raises: Exception – scaler has not been fitted