com.clust4j.algo.preprocess.MedianCenterer.java Source code

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Here is the source code for com.clust4j.algo.preprocess.MedianCenterer.java

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/*******************************************************************************
 *    Copyright 2015, 2016 Taylor G Smith
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 *******************************************************************************/

package com.clust4j.algo.preprocess;

import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.linear.Array2DRowRealMatrix;
import org.apache.commons.math3.linear.RealMatrix;

import com.clust4j.except.ModelNotFitException;
import com.clust4j.utils.MatUtils;
import com.clust4j.utils.VecUtils;

public class MedianCenterer extends Transformer {
    private static final long serialVersionUID = -5983524673626323084L;
    volatile protected double[] medians;

    private MedianCenterer(MedianCenterer mc) {
        this.medians = VecUtils.copy(mc.medians);
    }

    public MedianCenterer() {
    }

    @Override
    protected void checkFit() {
        if (null == medians)
            throw new ModelNotFitException("model not yet fit");
    }

    @Override
    public RealMatrix inverseTransform(RealMatrix X) {
        checkFit();

        // This effectively copies, so no need to do a copy later
        double[][] data = X.getData();
        final int m = data.length;
        final int n = data[0].length;

        if (n != medians.length)
            throw new DimensionMismatchException(n, medians.length);

        for (int j = 0; j < n; j++) {
            for (int i = 0; i < m; i++) {
                data[i][j] += medians[j];
            }
        }

        return new Array2DRowRealMatrix(data, false);
    }

    @Override
    public MedianCenterer copy() {
        return new MedianCenterer(this);
    }

    @Override
    public MedianCenterer fit(RealMatrix X) {
        synchronized (fitLock) {
            final int n = X.getColumnDimension();

            // need to mean center...
            this.medians = new double[n];
            final double[][] y = X.transpose().getData();

            // First pass, compute median...
            for (int j = 0; j < n; j++) {
                this.medians[j] = VecUtils.median(y[j]);
            }

            return this;
        }
    }

    @Override
    public RealMatrix transform(RealMatrix data) {
        return new Array2DRowRealMatrix(transform(data.getData()), false);
    }

    @Override
    public double[][] transform(double[][] data) {
        checkFit();
        MatUtils.checkDimsForUniformity(data);

        final int m = data.length;
        final int n = data[0].length;

        if (n != medians.length)
            throw new DimensionMismatchException(n, medians.length);

        double[][] X = new double[m][n];
        // subtract to center:
        for (int j = 0; j < n; j++) {
            for (int i = 0; i < m; i++) {
                X[i][j] = data[i][j] - medians[j];
            }
        }

        // assign
        return X;
    }
}