/**
* Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies
*
* Please see distribution for license.
*/
package com.opengamma.analytics.financial.timeseries.filter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.opengamma.analytics.financial.timeseries.analysis.DoubleTimeSeriesStatisticsCalculator;
import com.opengamma.analytics.math.statistics.descriptive.MeanCalculator;
import com.opengamma.analytics.math.statistics.descriptive.SampleStandardDeviationCalculator;
import com.opengamma.timeseries.date.localdate.ImmutableLocalDateDoubleTimeSeries;
import com.opengamma.timeseries.date.localdate.LocalDateDoubleEntryIterator;
import com.opengamma.timeseries.date.localdate.LocalDateDoubleTimeSeries;
import com.opengamma.util.ArgumentChecker;
/**
* Filter that partitions the time-series points based on standard deviation.
*/
public class StandardDeviationDoubleTimeSeriesFilter extends TimeSeriesFilter {
/** Logger. */
private static final Logger s_logger = LoggerFactory.getLogger(StandardDeviationDoubleTimeSeriesFilter.class);
private static final LocalDateDoubleTimeSeries EMPTY_SERIES = ImmutableLocalDateDoubleTimeSeries.EMPTY_SERIES;
private final DoubleTimeSeriesStatisticsCalculator _meanCalculator = new DoubleTimeSeriesStatisticsCalculator(new MeanCalculator());
private final DoubleTimeSeriesStatisticsCalculator _stdCalculator = new DoubleTimeSeriesStatisticsCalculator(new SampleStandardDeviationCalculator());
private double _standardDeviations;
/**
* Creates an instance.
*
* @param standardDeviations the standard deviations. zero or greater
*/
public StandardDeviationDoubleTimeSeriesFilter(final double standardDeviations) {
if (standardDeviations < 0) {
s_logger.info("Standard deviation was negative; using absolute value");
}
_standardDeviations = Math.abs(standardDeviations);
}
//-------------------------------------------------------------------------
public void setStandardDeviations(final double standardDeviations) {
if (standardDeviations < 0) {
s_logger.info("Standard deviation was negative; using absolute value");
}
_standardDeviations = Math.abs(standardDeviations);
}
//-------------------------------------------------------------------------
@Override
public FilteredTimeSeries evaluate(final LocalDateDoubleTimeSeries ts) {
ArgumentChecker.notNull(ts, "ts");
if (ts.isEmpty()) {
s_logger.info("Time series was empty");
return new FilteredTimeSeries(EMPTY_SERIES, EMPTY_SERIES);
}
final double mean = _meanCalculator.evaluate(ts);
final double std = _stdCalculator.evaluate(ts);
final int n = ts.size();
final int[] filteredDates = new int[n];
final double[] filteredData = new double[n];
final int[] rejectedDates = new int[n];
final double[] rejectedData = new double[n];
final LocalDateDoubleEntryIterator it = ts.iterator();
int i = 0, j = 0;
while (it.hasNext()) {
int date = it.nextTimeFast();
double value = it.currentValue();
if (Math.abs(value - mean) > _standardDeviations * std) {
rejectedDates[j] = date;
rejectedData[j++] = value;
} else {
filteredDates[i] = date;
filteredData[i++] = value;
}
}
return getFilteredSeries(filteredDates, filteredData, i, rejectedDates, rejectedData, j);
}
}