/*
* Copyright (c) 2015 Villu Ruusmann
*
* This file is part of JPMML-SkLearn
*
* JPMML-SkLearn 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-SkLearn 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-SkLearn. If not, see <http://www.gnu.org/licenses/>.
*/
package sklearn.preprocessing;
import java.util.ArrayList;
import java.util.List;
import org.dmg.pmml.DerivedField;
import org.dmg.pmml.Expression;
import org.jpmml.converter.ContinuousFeature;
import org.jpmml.converter.Feature;
import org.jpmml.converter.PMMLUtil;
import org.jpmml.converter.ValueUtil;
import org.jpmml.sklearn.ClassDictUtil;
import org.jpmml.sklearn.SkLearnEncoder;
import sklearn.HasNumberOfFeatures;
import sklearn.Transformer;
public class MinMaxScaler extends Transformer implements HasNumberOfFeatures {
public MinMaxScaler(String module, String name){
super(module, name);
}
@Override
public int getNumberOfFeatures(){
int[] shape = getScaleShape();
return shape[0];
}
@Override
public List<Feature> encodeFeatures(List<Feature> features, SkLearnEncoder encoder){
List<? extends Number> min = getMin();
List<? extends Number> scale = getScale();
ClassDictUtil.checkSize(features, min, scale);
List<Feature> result = new ArrayList<>();
for(int i = 0; i < features.size(); i++){
Feature feature = features.get(i);
Number minValue = min.get(i);
Number scaleValue = scale.get(i);
if(ValueUtil.isOne(scaleValue) && ValueUtil.isZero(minValue)){
result.add(feature);
continue;
}
ContinuousFeature continuousFeature = feature.toContinuousFeature();
// "($name * scale) + min"
Expression expression = continuousFeature.ref();
if(!ValueUtil.isOne(scaleValue)){
expression = PMMLUtil.createApply("*", expression, PMMLUtil.createConstant(scaleValue));
} // End if
if(!ValueUtil.isZero(minValue)){
expression = PMMLUtil.createApply("+", expression, PMMLUtil.createConstant(minValue));
}
DerivedField derivedField = encoder.createDerivedField(createName(continuousFeature), expression);
result.add(new ContinuousFeature(encoder, derivedField));
}
return result;
}
public List<? extends Number> getMin(){
return (List)ClassDictUtil.getArray(this, "min_");
}
public List<? extends Number> getScale(){
return (List)ClassDictUtil.getArray(this, "scale_");
}
private int[] getScaleShape(){
return ClassDictUtil.getShape(this, "scale_", 1);
}
}