[Jrobin-commits] src/org/jrobin/graph LinearInterpolator.java,1.1,1.2

[Sasa M. <sa...@us...>]

Update of /cvsroot/jrobin/src/org/jrobin/graph
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv3796/org/jrobin/graph

Modified Files:
	LinearInterpolator.java 
Log Message:
New interpolation method (INTERPOLATE_BESTFIT - best fit straight line). More PlottableDemo graphs

Index: LinearInterpolator.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/graph/LinearInterpolator.java,v
retrieving revision 1.1
retrieving revision 1.2
diff -C2 -d -r1.1 -r1.2
*** LinearInterpolator.java	20 Jan 2004 09:09:33 -0000	1.1
--- LinearInterpolator.java	9 Jun 2004 08:59:23 -0000	1.2
***************
*** 36,40 ****
   * Interpolation algorithm returns different values based on the value passed to
   * {@link #setInterpolationMethod(int) setInterpolationMethod()}. If not set, interpolation
!  * method defaults to standard linear interpolation. Interpolation method handles NaN datasource
   * values gracefully.<p>
   *
--- 36,41 ----
   * Interpolation algorithm returns different values based on the value passed to
   * {@link #setInterpolationMethod(int) setInterpolationMethod()}. If not set, interpolation
!  * method defaults to standard linear interpolation ({@link #INTERPOLATE_LINEAR}).
!  * Interpolation method handles NaN datasource
   * values gracefully.<p>
   *
***************
*** 52,58 ****
  	 * See {@link #setInterpolationMethod(int) setInterpolationMethod()} for explanation. */
  	public static final int INTERPOLATE_LINEAR = 2;
  
  	private int lastIndexUsed = 0;
- 
  	private int interpolationMethod = INTERPOLATE_LINEAR;
  
--- 53,61 ----
  	 * See {@link #setInterpolationMethod(int) setInterpolationMethod()} for explanation. */
  	public static final int INTERPOLATE_LINEAR = 2;
+ 	/** constant used to specify LINEAR REGRESSION as interpolation method.
+ 	 * See {@link #setInterpolationMethod(int) setInterpolationMethod()} for explanation. */
+ 	public static final int INTERPOLATE_REGRESSION = 3;
  
  	private int lastIndexUsed = 0;
  	private int interpolationMethod = INTERPOLATE_LINEAR;
  
***************
*** 60,63 ****
--- 63,69 ----
  	private double[] values;
  
+ 	// used only if INTERPOLATE_BESTFIT is specified
+ 	double b0 = Double.NaN, b1 = Double.NaN;
+ 
  	/**
  	 * Creates LinearInterpolator from arrays of timestamps and corresponding datasource values.
***************
*** 129,138 ****
  	 * <li><code>INTERPOLATE_LINEAR: 200</code>
  	 * </ul>
! 	 * If not set, interpolation method defaults to <code>INTERPOLATE_LINEAR</code>.
  	 * @param interpolationMethod Should be <code>INTERPOLATE_LEFT</code>,
! 	 * <code>INTERPOLATE_RIGHT</code> or <code>INTERPOLATE_LINEAR</code>.
  	 */
  	public void setInterpolationMethod(int interpolationMethod) {
! 		this.interpolationMethod = interpolationMethod;
  	}
  
--- 135,195 ----
  	 * <li><code>INTERPOLATE_LINEAR: 200</code>
  	 * </ul>
! 	 * If not set, interpolation method defaults to <code>INTERPOLATE_LINEAR</code>.<p>
! 	 *
! 	 * The fourth available interpolation method is INTERPOLATE_REGRESSION. This method uses
! 	 * simple linear regression to interpolate supplied data with a simple straight line which does not
! 	 * necessarily pass through all data points. The slope of the best-fit line will be chosen so that the
! 	 * total square distance of real data points from from the best-fit line is at minimum.<p>
! 	 *
! 	 * The full explanation of this inteprolation method can be found
! 	 * <a href="http://www.tufts.edu/~gdallal/slr.htm">here</a>.<p>
! 	 *
  	 * @param interpolationMethod Should be <code>INTERPOLATE_LEFT</code>,
! 	 * <code>INTERPOLATE_RIGHT</code>, <code>INTERPOLATE_LINEAR</code> or
! 	 * <code>INTERPOLATE_REGRESSION</code>. Any other value will be interpreted as
! 	 * INTERPOLATE_LINEAR.
  	 */
  	public void setInterpolationMethod(int interpolationMethod) {
! 		switch(interpolationMethod) {
! 			case INTERPOLATE_REGRESSION:
! 				calculateBestFitLine();
! 			case INTERPOLATE_LEFT:
! 			case INTERPOLATE_RIGHT:
! 			case INTERPOLATE_LINEAR:
! 				this.interpolationMethod = interpolationMethod;
! 				break;
! 			default:
! 				this.interpolationMethod = INTERPOLATE_LINEAR;
! 		}
! 	}
! 
! 	private void calculateBestFitLine() {
! 		int count = timestamps.length, validCount = 0;
! 		double ts = 0.0, vs = 0.0;
! 		for(int i = 0; i < count; i++) {
! 			if(!Double.isNaN(values[i])) {
! 				ts += timestamps[i];
! 				vs += values[i];
! 				validCount++;
! 			}
! 		}
! 		if(validCount <= 1) {
! 			// just one not-NaN point
! 			b0 = b1 = Double.NaN;
! 			return;
! 		}
! 		ts /= validCount;
! 		vs /= validCount;
! 		double s1 = 0, s2 = 0;
! 		for(int i = 0; i < count; i++) {
! 			if(!Double.isNaN(values[i])) {
! 				double dt = timestamps[i] - ts;
! 				double dv = values[i] - vs;
! 				s1 += dt * dv;
! 				s2 += dt * dt;
! 			}
! 		}
! 		b1 = s1 / s2;
! 		b0 = vs - b1 * ts;
  	}
  
***************
*** 144,147 ****
--- 201,207 ----
  	 */
  	public double getValue(long timestamp) {
+ 		if(interpolationMethod == INTERPOLATE_REGRESSION) {
+ 			return b0 + b1 * timestamp;
+ 		}
  		int count = timestamps.length;
  		// check if out of range