code: public static DiscreteFactor centerFeatures(DiscreteFactor featureFactor, int featureVariableNum) {
      return featureFactor.add(getMeans(featureFactor, featureVariableNum).product(-1.0)).coerceToDiscrete();
    }
docs: Computes the empirical mean of the features in {@code featureFactor}, then
  subtracts that mean from each feature.
  
  @param featureFactor
  @param featureVariableNum
  @return