# Example (JKQTPlotter): Very simple line-graph {#JKQTPlotterSimpleTest} This project (see `./examples/simpletest/`) simply creates a JKQTPlotter widget (as a new window) and adds a single line-graph (a sine-wave). Data is initialized from two QVector<double> objects. The source code of the main application is (see [`jkqtplotter_simpletest.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/simpletest/jkqtplotter_simpletest.cpp): ```.cpp #include <QApplication> #include "jkqtplotter/jkqtplotter.h" int main(int argc, char* argv[]) { QApplication app(argc, argv); // 1. create a plotter window and get a pointer to the internal datastore // (for convenience) JKQTPlotter plot; JKQTPDatastore* ds=plot.getDatastore(); // 2. now we create data for a simple plot (a sine curve) QVector<double> X, Y; const int Ndata=100; for (int i=0; i<Ndata; i++) { const double x=double(i)/double(Ndata)*8.0*M_PI; X<<x; Y<<sin(x); } // 3. make data available to JKQTPlotter by adding it to the internal // datastore. // Note: In this step the data is copied (of not specified otherwise), so // you can reuse X and Y afterwards! // The variables columnX and columnY will contain the internal column ID // of the newlycreated columns with names "x" and "y" and the (copied) // data from X and Y. size_t columnX=ds->addCopiedColumn(X, "x"); size_t columnY=ds->addCopiedColumn(Y, "y"); // 4. create a graph in the plot, which plots the dataset X/Y: JKQTPXYLineGraph* graph1=new JKQTPXYLineGraph(&plot); graph1->setXColumn(columnX); graph1->setYColumn(columnY); graph1->setTitle(QObject::tr("sine graph")); // 5. add the graph to the plot, so it is actually displayed plot.addGraph(graph1); // 6. autoscale the plot so the graph is contained plot.zoomToFit(); // show plotter and make it a decent size plot.show(); plot.resize(600,400); return app.exec(); } ``` The result looks like this: ![simpletest](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/simpletest.png)