private void computeCoefficientOfDetermination() {
int numberOfItems = scatterpointsDataset.getSeries(0).getItemCount();
double arithmeticMeanOfX = 0; // arithmetic mean of X
double arithmeticMeanOfY = 0; // arithmetic mean of Y
double varX = 0; // variance of X
double varY = 0; // variance of Y
double coVarXY = 0; // covariance of X and Y;
// compute arithmetic means
for (int i = 0; i < numberOfItems; i++) {
arithmeticMeanOfX += scatterpointsDataset.getXValue(0, i);
arithmeticMeanOfY += scatterpointsDataset.getYValue(0, i);
}
arithmeticMeanOfX /= numberOfItems;
arithmeticMeanOfY /= numberOfItems;
// compute variances and covariance
for (int i = 0; i < numberOfItems; i++) {
varX += Math.pow(scatterpointsDataset.getXValue(0, i) - arithmeticMeanOfX, 2);
varY += Math.pow(scatterpointsDataset.getYValue(0, i) - arithmeticMeanOfY, 2);
coVarXY +=
(scatterpointsDataset.getXValue(0, i) - arithmeticMeanOfX)
* (scatterpointsDataset.getYValue(0, i) - arithmeticMeanOfY);
}
// computation of coefficient of determination
double r2 = Math.pow(coVarXY, 2) / (varX * varY);
r2 = MathUtils.round(r2, Math.pow(10.0, 5));
final double[] coefficients = Regression.getOLSRegression(scatterpointsDataset, 0);
final double intercept = coefficients[0];
final double slope = coefficients[1];
final String linearEquation;
if (intercept >= 0) {
linearEquation = "y = " + (float) slope + "x + " + (float) intercept;
} else {
linearEquation = "y = " + (float) slope + "x - " + Math.abs((float) intercept);
}
TextTitle tt = new TextTitle(linearEquation + "\nR² = " + r2);
tt.setTextAlignment(HorizontalAlignment.RIGHT);
tt.setFont(chart.getLegend().getItemFont());
tt.setBackgroundPaint(new Color(200, 200, 255, 100));
tt.setFrame(new BlockBorder(Color.white));
tt.setPosition(RectangleEdge.BOTTOM);
r2Annotation = new XYTitleAnnotation(0.98, 0.02, tt, RectangleAnchor.BOTTOM_RIGHT);
r2Annotation.setMaxWidth(0.48);
getPlot().addAnnotation(r2Annotation);
}
public static void getListInEvenlySpacedGrid(
final int sceneRasterWidth,
final int sceneRasterHeight,
final int sourceGridWidth,
final int sourceGridHeight,
final int[] x,
final int[] y,
final double[] sourcePointList,
final int targetGridWidth,
final int targetGridHeight,
final double subSamplingX,
final double subSamplingY,
final float[] targetPointList) {
if (sourcePointList.length != sourceGridWidth * sourceGridHeight) {
throw new IllegalArgumentException(
"Original tie point array size does not match 'sourceGridWidth' x 'sourceGridHeight'");
}
if (targetPointList.length != targetGridWidth * targetGridHeight) {
throw new IllegalArgumentException(
"Target tie point array size does not match 'targetGridWidth' x 'targetGridHeight'");
}
int k = 0;
for (int r = 0; r < targetGridHeight; r++) {
double newY = r * subSamplingY;
if (newY > sceneRasterHeight - 1) {
newY = sceneRasterHeight - 1;
}
double oldY0 = 0, oldY1 = 0;
int j0 = 0, j1 = 0;
for (int rr = 1; rr < sourceGridHeight; rr++) {
j0 = rr - 1;
j1 = rr;
oldY0 = y[j0 * sourceGridWidth];
oldY1 = y[j1 * sourceGridWidth];
if (oldY1 > newY) {
break;
}
}
final double wj = (newY - oldY0) / (oldY1 - oldY0);
for (int c = 0; c < targetGridWidth; c++) {
double newX = c * subSamplingX;
if (newX > sceneRasterWidth - 1) {
newX = sceneRasterWidth - 1;
}
double oldX0 = 0, oldX1 = 0;
int i0 = 0, i1 = 0;
for (int cc = 1; cc < sourceGridWidth; cc++) {
i0 = cc - 1;
i1 = cc;
oldX0 = x[i0];
oldX1 = x[i1];
if (oldX1 > newX) {
break;
}
}
final double wi = (newX - oldX0) / (oldX1 - oldX0);
targetPointList[k++] =
(float)
(MathUtils.interpolate2D(
wi,
wj,
sourcePointList[i0 + j0 * sourceGridWidth],
sourcePointList[i1 + j0 * sourceGridWidth],
sourcePointList[i0 + j1 * sourceGridWidth],
sourcePointList[i1 + j1 * sourceGridWidth]));
}
}
}