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58 lines
1.9 KiB
Markdown
58 lines
1.9 KiB
Markdown
# Example (JKQTPlotter): Very simple scatter-graph {#JKQTPlotterscatter}
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This project (see `./examples/scatter/`) simply creates a JKQTPlotter widget (as a new window) and adds a single scatter graph of type JKQTPXYScatterGraph (a sine-wave with noise).
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The source code of the example can be found in [`jkqtplotter_scatter.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/scatter/scatter.cpp).
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First we create a plotter window and get a pointer to the internal datastore (for convenience):
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```.cpp
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JKQTPlotter plot;
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JKQTPDatastore* ds=plot.getDatastore();
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```
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Now we add two columns to the JKQTPDatastore and obtain back-inserter iterators for these:
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```.cpp
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size_t columnX=ds->addColumn("x");
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auto colXInserter=ds->backInserter(columnX);
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size_t columnY=ds->addColumn("y");
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auto colYInserter=ds->backInserter(columnY);
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```
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Now we create data for a simple plot (a sine curve with random noise):
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```.cpp
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std::default_random_engine generator;
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std::normal_distribution<double> distribution(0,0.5);
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const int Ndata=100;
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for (int i=0; i<Ndata; i++) {
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// put data
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const double x=double(i)/double(Ndata)*8.0*JKQTPSTATISTICS_PI;
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*colXInserter=x;
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*colYInserter=sin(x)+distribution(generator);
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// advance back-inserters
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colXInserter++;
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colYInserter++;
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}
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```
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Here we create a graph in the plot, which plots the dataset X/Y:
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```.cpp
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JKQTPXYScatterGraph* graph1=new JKQTPXYScatterGraph(&plot);
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graph1->setXColumn(columnX);
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graph1->setYColumn(columnY);
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graph1->setTitle(QObject::tr("sine graph"));
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```
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Now we add the graph to the plot, so it is actually displayed:
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```.cpp
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plot.addGraph(graph1);
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```
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Finally we autoscale the plot so the graph is contained:
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```.cpp
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plot.zoomToFit();
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```
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The result looks like this:
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