org.mrgeo.aggregators.ModeAggregator.java Source code

Introduction

Here is the source code for org.mrgeo.aggregators.ModeAggregator.java

Source

/*
 * Copyright 2009-2016 DigitalGlobe, Inc.
 *
 * 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 org.mrgeo.aggregators;

import org.apache.commons.lang3.NotImplementedException;

import java.util.HashMap;
import java.util.Map;

/**
 * Returns the mode of pixel values.
 * No data values will be excluded.
 */
public class ModeAggregator implements Aggregator {

    @Override
    public double aggregate(double[] values, double nodata) {
        HashMap<Double, Integer> freqs = new HashMap<Double, Integer>();

        for (double val : values) {
            if (Double.compare(val, nodata) != 0) {
                Integer freq = freqs.get(val);
                freqs.put(val, (freq == null ? 1 : freq + 1));
            }
        }

        double mode = nodata;
        int maxFreq = 0;

        for (Map.Entry<Double, Integer> entry : freqs.entrySet()) {
            int freq = entry.getValue();
            if (freq > maxFreq) {
                maxFreq = freq;
                mode = entry.getKey();
            }
        }

        return mode;
    }

    @Override
    public float aggregate(float[] values, float nodata) {
        HashMap<Float, Integer> freqs = new HashMap<Float, Integer>();

        for (float val : values) {
            if (Float.compare(val, nodata) != 0) {
                Integer freq = freqs.get(val);
                freqs.put(val, (freq == null ? 1 : freq + 1));
            }
        }

        float mode = nodata;
        int maxFreq = 0;

        for (Map.Entry<Float, Integer> entry : freqs.entrySet()) {
            int freq = entry.getValue();
            if (freq > maxFreq) {
                maxFreq = freq;
                mode = entry.getKey();
            }
        }

        return mode;
    }

    @Override
    public int aggregate(int[] values, int nodata) {
        HashMap<Integer, Integer> freqs = new HashMap<Integer, Integer>();

        for (int val : values) {
            if (val != nodata) {
                Integer freq = freqs.get(val);
                freqs.put(val, (freq == null ? 1 : freq + 1));
            }
        }

        int mode = nodata;
        int maxFreq = 0;

        for (Map.Entry<Integer, Integer> entry : freqs.entrySet()) {
            int freq = entry.getValue();
            if (freq > maxFreq) {
                maxFreq = freq;
                mode = entry.getKey();
            }
        }

        return mode;
    }

    @Override
    public double aggregate(double[][] values, double weightx, double weighty, double nodata) {
        throw new NotImplementedException("Not yet implemented");
    }

    @Override
    public float aggregate(float[][] values, double weightx, double weighty, float nodata) {
        throw new NotImplementedException("Not yet implemented");
    }

    @Override
    public int aggregate(final int[][] values, final double weightx, final double weighty, final int nodata) {
        throw new NotImplementedException("Not yet implemented");
    }

}