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JPMML R to PMML converter
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/*
 * Copyright (c) 2016 Villu Ruusmann
 *
 * This file is part of JPMML-R
 *
 * JPMML-R is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * JPMML-R is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with JPMML-R.  If not, see .
 */
package org.jpmml.rexp;

import java.util.ArrayList;
import java.util.List;

import org.dmg.pmml.Model;
import org.jpmml.converter.Feature;
import org.jpmml.converter.Schema;
import org.jpmml.converter.SchemaUtil;
import org.jpmml.converter.regression.RegressionModelUtil;

public class LMConverter extends ModelConverter {

	private Formula formula = null;


	public LMConverter(RGenericVector lm){
		super(lm);
	}

	@Override
	public void encodeSchema(RExpEncoder encoder){
		RGenericVector lm = getObject();

		RGenericVector xlevels = lm.getGenericElement("xlevels", false);
		RGenericVector model = lm.getGenericElement("model", false);
		RGenericVector data = lm.getGenericElement("data", false);

		RExp terms;

		FormulaContext context;

		if(model != null){
			terms = model.getAttribute("terms");

			context = new ModelFrameFormulaContext(model){

				@Override
				public List getCategories(String variable){

					if(xlevels != null && xlevels.hasElement(variable)){
						RStringVector levels = xlevels.getStringElement(variable);

						return levels.getValues();
					}

					return super.getCategories(variable);
				}

				@Override
				public RVector getData(String variable){

					if(data != null && data.hasElement(variable)){
						return data.getVectorElement(variable);
					}

					return super.getData(variable);
				}
			};
		} else

		{
			terms = lm.getElement("terms");

			context = new FormulaContext(){

				@Override
				public List getCategories(String variable){

					if(xlevels != null && xlevels.hasElement(variable)){
						RStringVector levels = xlevels.getStringElement(variable);

						return levels.getValues();
					}

					return null;
				}

				@Override
				public RVector getData(String variable){

					if(data != null && data.hasElement(variable)){
						return data.getVectorElement(variable);
					}

					return null;
				}
			};
		}

		encodeSchema(terms, context, encoder);
	}

	protected void encodeSchema(RExp terms, FormulaContext context, RExpEncoder encoder){
		Formula formula = FormulaUtil.createFormula(terms, context, encoder);

		FormulaUtil.setLabel(formula, terms, null, encoder);

		List names = FormulaUtil.removeSpecialSymbol(getCoefficientNames(), getInterceptName());

		FormulaUtil.addFeatures(formula, names, true, encoder);

		this.formula = formula;
	}

	@Override
	public Model encodeModel(Schema schema){
		RGenericVector lm = getObject();

		RDoubleVector coefficients = lm.getDoubleElement("coefficients");

		Double intercept = coefficients.getElement(getInterceptName(), false);

		List features = schema.getFeatures();

		SchemaUtil.checkSize(coefficients.size() - (intercept != null ? 1 : 0), features);

		List featureCoefficients = getFeatureCoefficients(features, coefficients);

		return RegressionModelUtil.createRegression(features, featureCoefficients, intercept, null, schema);
	}

	public String getInterceptName(){
		return LMConverter.INTERCEPT;
	}

	public List getCoefficientNames(){
		RGenericVector lm = getObject();

		RDoubleVector coefficients = lm.getDoubleElement("coefficients");

		RStringVector coefficientNames = coefficients.names();

		return coefficientNames.getDequotedValues();
	}

	public List getFeatureCoefficients(List features, RDoubleVector coefficients){
		List result = new ArrayList<>();

		for(Feature feature : features){
			Double coefficient = getFeatureCoefficient(feature, coefficients);

			result.add(coefficient);
		}

		return result;
	}

	public Double getFeatureCoefficient(Feature feature, RDoubleVector coefficients){
		return this.formula.getCoefficient(feature, coefficients);
	}

	public static final String INTERCEPT = "(Intercept)";
}