code: public static FeatureStandardizer estimateFrom(DiscreteFactor featureFactor, int featureVariableNum,
        Assignment biasFeature, double rescalingFactor) {
      return FeatureStandardizer.estimateFrom(Arrays.asList(featureFactor), featureVariableNum,
          biasFeature, rescalingFactor);
    }
docs: Estimates standardization parameters (empirical feature means and
  variances) from {@code featureFactor}. Each assignment to the
  non-feature variables in {@code featureFactor} corresponds to a
  feature vector.
  
  @param featureFactor
  @param featureVariableNum
  @param biasFeature If {@code null} no bias feature is used.
  @param rescalingFactor amount by which to multiply each feature vector after
  standardization.
  @return