normalizer.java

jrobin,使用纯java实现的RRD数据库,使用RRD数据库来统计数据.

/* ============================================================
 * JRobin : Pure java implementation of RRDTool's functionality
 * ============================================================
 *
 * Project Info:  http://www.jrobin.org
 * Project Lead:  Sasa Markovic ([e-mail]);
 *
 * (C) Copyright 2003-2005, by Sasa Markovic.
 *
 * Developers:    Sasa Markovic ([e-mail])
 *
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 */

package org.jrobin.graph;

import org.jrobin.core.Util;

import java.util.Arrays;

class Normalizer {
	final private double[] timestamps;
	final int count;
	final double step;

	Normalizer(long tStart, long tEnd, int count) {
		this.count = count;
		this.step = (tEnd - tStart) / (count - 1);
		this.timestamps = new double[count];
		for (int i = 0; i < count; i++) {
			this.timestamps[i] = tStart + ((double) i / (double) (count - 1)) * (tEnd - tStart);
		}
	}

	double[] getTimestamps() {
		return timestamps;
	}

	double[] normalize(long[] rawTimestamps, double[] rawValues) {
		int rawCount = rawTimestamps.length;
		long rawStep = rawTimestamps[1] - rawTimestamps[0];
		// check if we have a simple match
		if (rawCount == count && rawStep == step && rawTimestamps[0] == timestamps[0]) {
			return getCopyOf(rawValues);
		}
		// reset all normalized values to NaN
		double[] values = new double[count];
		Arrays.fill(values, Double.NaN);
		for (int rawSeg = 0, seg = 0; rawSeg < rawCount && seg < count; rawSeg++) {
			double rawValue = rawValues[rawSeg];
			if (!Double.isNaN(rawValue)) {
				long rawLeft = rawTimestamps[rawSeg] - rawStep;
				while (seg < count && rawLeft >= timestamps[seg]) {
					seg++;
				}
				boolean overlap = true;
				for (int fillSeg = seg; overlap && fillSeg < count; fillSeg++) {
					double left = timestamps[fillSeg] - step;
					double t1 = Math.max(rawLeft, left);
					double t2 = Math.min(rawTimestamps[rawSeg], timestamps[fillSeg]);
					if (t1 < t2) {
						values[fillSeg] = Util.sum(values[fillSeg], (t2 - t1) * rawValues[rawSeg]);
					}
					else {
						overlap = false;
					}
				}
			}
		}
		for (int seg = 0; seg < count; seg++) {
			values[seg] /= step;
		}
		return values;
	}

	private static double[] getCopyOf(double[] rawValues) {
		int n = rawValues.length;
		double[] values = new double[n];
		System.arraycopy(rawValues, 0, values, 0, n);
		return values;
	}
}