com.rapidminer.operator.preprocessing.RemoveUnusedNominalValuesOperator.java Source code

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Here is the source code for com.rapidminer.operator.preprocessing.RemoveUnusedNominalValuesOperator.java

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/**
 * Copyright (C) 2001-2017 by RapidMiner and the contributors
 * 
 * Complete list of developers available at our web site:
 * 
 * http://rapidminer.com
 * 
 * This program 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.
 * 
 * This program 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 this program.
 * If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.operator.preprocessing;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang.ArrayUtils;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.Statistics;
import com.rapidminer.example.table.NominalMapping;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.OperatorVersion;
import com.rapidminer.operator.ports.metadata.AttributeMetaData;
import com.rapidminer.operator.ports.metadata.ExampleSetMetaData;
import com.rapidminer.operator.ports.metadata.SetRelation;
import com.rapidminer.operator.preprocessing.RemoveUnusedNominalValuesModel.MappingTranslation;
import com.rapidminer.parameter.ParameterType;
import com.rapidminer.parameter.ParameterTypeBoolean;
import com.rapidminer.parameter.UndefinedParameterError;
import com.rapidminer.tools.Ontology;

/**
 * This operator will remove each unused (=not occurring) nominal value from the mapping.
 *
 * @author Sebastian Land
 */
public class RemoveUnusedNominalValuesOperator extends PreprocessingOperator {

    private static final String PARAMETER_SORT_MAPPING_ALPHABETICALLY = "sort_alphabetically";

    /**
     * Incompatible version, old version writes into the exampleset, if original output port is not
     * connected.
     */
    private static final OperatorVersion VERSION_MAY_WRITE_INTO_DATA = new OperatorVersion(7, 1, 1);

    public RemoveUnusedNominalValuesOperator(OperatorDescription description) {
        super(description);
    }

    @Override
    protected Collection<AttributeMetaData> modifyAttributeMetaData(ExampleSetMetaData emd, AttributeMetaData amd)
            throws UndefinedParameterError {
        amd.setValueSetRelation(SetRelation.SUBSET);
        return Collections.singleton(amd);
    }

    @Override
    public PreprocessingModel createPreprocessingModel(ExampleSet exampleSet) throws OperatorException {
        boolean sortMappings = getParameterAsBoolean(PARAMETER_SORT_MAPPING_ALPHABETICALLY);

        Map<String, MappingTranslation> translations = new HashMap<String, MappingTranslation>();

        exampleSet.recalculateAllAttributeStatistics();
        for (Attribute attribute : exampleSet.getAttributes()) {

            if (attribute.isNominal()) {
                MappingTranslation translation = new MappingTranslation(
                        (NominalMapping) attribute.getMapping().clone());
                for (String value : attribute.getMapping().getValues()) {
                    double count = exampleSet.getStatistics(attribute, Statistics.COUNT, value);
                    if (count > 0) {
                        translation.newMapping.mapString(value);
                    }
                }
                if (translation.newMapping.size() < attribute.getMapping().size()) {
                    if (sortMappings) {
                        translation.newMapping.sortMappings();
                    }
                    translations.put(attribute.getName(), translation);
                }
            }
        }
        return new RemoveUnusedNominalValuesModel(exampleSet, translations);
    }

    @Override
    protected int[] getFilterValueTypes() {
        return new int[] { Ontology.NOMINAL };
    }

    @Override
    public Class<? extends PreprocessingModel> getPreprocessingModelClass() {
        return RemoveUnusedNominalValuesModel.class;
    }

    @Override
    public List<ParameterType> getParameterTypes() {
        List<ParameterType> types = super.getParameterTypes();

        types.add(new ParameterTypeBoolean(PARAMETER_SORT_MAPPING_ALPHABETICALLY,
                "If checked, the resulting mapping will be sorted alphabetically.", true, false));

        return types;
    }

    @Override
    public boolean writesIntoExistingData() {
        if (getCompatibilityLevel().isAbove(VERSION_MAY_WRITE_INTO_DATA)) {
            return false;
        } else {
            // old version: true only if original output port is connected
            return isOriginalOutputConnected() && super.writesIntoExistingData();
        }
    }

    @Override
    public OperatorVersion[] getIncompatibleVersionChanges() {
        return (OperatorVersion[]) ArrayUtils.addAll(super.getIncompatibleVersionChanges(),
                new OperatorVersion[] { VERSION_MAY_WRITE_INTO_DATA });
    }
}