'Get feature names from all transformers.
Returns
feature_names : list of strings
Names of the features produced by transform.'

def get_feature_names(self):

    feature_names = []
    for (name, trans, weight) in self._iter():
        if (not hasattr(trans, 'get_feature_names')):
            raise AttributeError(('Transformer    %s    (type    %s)    does    not    provide    get_feature_names.' % (str(name), type(trans).__name__)))
        feature_names.extend([((name + '__') + f) for f in trans.get_feature_names()])
    return feature_names
