CorrelateTask.java

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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 net.redgeek.android.eventrend.backgroundtasks;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;

import net.redgeek.android.eventrend.graph.plugins.TimeSeriesCorrelator;
import net.redgeek.android.eventrend.primitives.TimeSeries;
import net.redgeek.android.eventrend.util.Number;

/**
 * Performs a correlation of data according the the Correlator that has been set
 * for the TimeSeriesCorrleator.setCorrelator. After the correlation is
 * complete, this also orders the correlations from highest correlation to
 * lowest, and returns the result as a string.
 * 
 * <p>
 * Note that since this is "backgroundtask", no UI operations may be performed.
 * 
 * @author barclay
 * 
 */
public class CorrelateTask {
  private TimeSeriesCorrelator mCorrelator;
  private ArrayList<TimeSeries> mSeries;

  public String mOutput;

  public HashMap<Float, String> mOutputMap;

  public CorrelateTask() {
    mOutputMap = new HashMap<Float, String>();
  }

  public void setCorrelator(TimeSeriesCorrelator c) {
    mCorrelator = c;
  }

  public void setTimeSeries(ArrayList<TimeSeries> timeseries) {
    mSeries = timeseries;
  }

  public void correlate() {
    ArrayList<String> l;
    int nSeries = mSeries.size();
    HashMap<Float, ArrayList<String>> hm = new HashMap<Float, ArrayList<String>>();
    String[] categories = new String[nSeries];

    Float[][] correlations = mCorrelator.correlate(mSeries);

    for (int i = 0; i < nSeries; i++) {
      TimeSeries ts1 = mSeries.get(i);
      categories[i] = ts1.getDbRow().getCategoryName();
    }

    for (int i = 0; i < nSeries; i++) {
      for (int j = i + 1; j < nSeries; j++) {
        float key;
        Float corr = correlations[i][j];
        if (corr == null || corr.isNaN()) {
          key = 0.0f;
        } else {
          key = corr.floatValue();
        }

        l = hm.get(Math.abs(key));
        if (l == null) {
          l = new ArrayList<String>();
          hm.put(Math.abs(key), l);
        }

        key = Number.Round(corr, 3);
        String s = categories[i] + " and " + categories[j] + "\n  " + key
            + ": " + Number.LinearMatrixCorrelation.correlationToString(corr)
            + "\n";
        l.add(s);
      }
    }

    Map.Entry entry;
    SortedMap<Float, ArrayList<String>> sorted = new TreeMap<Float, ArrayList<String>>(
        java.util.Collections.reverseOrder());
    sorted.putAll(hm);
    Iterator iterator = sorted.entrySet().iterator();

    mOutput = "";
    while (iterator.hasNext()) {
      entry = (Map.Entry) iterator.next();
      l = (ArrayList<String>) entry.getValue();
      for (int i = 0; i < l.size(); i++) {
        mOutput += l.get(i);
      }
    }
  }
}