'Impute missing values in a feature set.
Parameters
features: array-like {n_samples, n_features}
A feature matrix
Returns
array-like {n_samples, n_features}'

def _impute_values(self, features):

    if (self.verbosity > 1):
        print('Imputing    missing    values    in    feature    set')
    if (self._fitted_imputer is None):
        self._fitted_imputer = Imputer(strategy='median', axis=1)
        self._fitted_imputer.fit(features)
    return self._fitted_imputer.transform(features)
