0e2237e92f
- fixed JKQTPColumnMathImage with modifiers - improved documentation - make use of link_prl/create_prl in QMake projects (see http://doc.qt.io/qt-5/qmake-advanced-usage.html)
2.5 KiB
Example (JKQTPlotter): Plotting Parametric Curves
This project (see ./examples/simpletest_parametriccurve/) demonstrates how to draw parametric curves, using [JKQTPXYLineGraph}(../simpletest) and JKQTPXYParametrizedScatterGraph.
The source code of the main application can be found in jkqtplotter_simpletest_parametriccurve.cpp. First, the parametric curve (here a logarithic spiral) is sampled into two columns containing the x- and y-values along the curve. In addition the radial distance from x=y=0 is added into a third column:
QVector<double> X, Y, R;
const int Ndata=500; // number of plot points in each curve
const double phiMax=4.0*M_PI;
const double a=1;
const double k=0.2;
for (double phi=-phiMax; phi<=phiMax; phi+=phiMax/double(Ndata)) {
const double x=a*exp(k*phi)*cos(phi);
const double y=a*exp(k*phi)*sin(phi);
X<<x;
Y<<y;
R<<sqrt(x*x+y*y);
}
// and copy it to the datastore
size_t columnX=ds->addCopiedColumn(X, "x");
size_t columnY=ds->addCopiedColumn(Y, "y");
size_t columnR=ds->addCopiedColumn(R, "r");
Then simples graph just uses the columns X and Y to plot the curve:
JKQTPXYLineGraph* graph1=new JKQTPXYLineGraph(&plot);
graph1->setXColumn(columnX);
graph1->setYColumn(columnY);
graph1->setDrawLine(true);
graph1->setSymbol(JKQTPNoSymbol);
graph1->setTitle("one-colored spiral");
plot.addGraph(graph1);
If you use JKQTPXYParametrizedScatterGraph instead of JKQTPXYLineGraph, you can also modify the color of the line-segments, connecting the datapoints:
JKQTPXYParametrizedScatterGraph* graph2=new JKQTPXYParametrizedScatterGraph(&plot2);
graph2->setXColumn(columnX);
graph2->setYColumn(columnY);
graph2->setColorColumn(columnR);
graph2->setPalette(JKQTPMathImageMATLAB);
graph2->setSymbol(JKQTPNoSymbol);
graph2->setDrawLine(true);
graph2->setTitle("colored spiral");
graph2->getColorBarRightAxis()->setAxisLabel("color scale radius $r(\\phi)$");
plot2.addGraph(graph2);
The result looks like this:
... and with the line-color set by the radius:
