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74 lines
3.6 KiB
Markdown
74 lines
3.6 KiB
Markdown
# Example (JKQTPlotter): Filled Graphs with Error Indicators {#JKQTPlotterFilledGraphsErrorBars}
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This project (see [`filledgraphs_errors`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/filledgraphs_errors) shows how to draw filled graphs with different styles of error indicators.
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The source code of the main application is (see [`filledgraphs_errors.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/filledgraphs_errors/filledgraphs_errors.cpp):
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```.cpp
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// 1. create a plotter window and get a pointer to the internal datastore (for convenience)
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JKQTPlotter plot;
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JKQTPDatastore* ds=plot.getDatastore();
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// 2. now we create three columns for key and value
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size_t columnK=ds->addLinearColumn(9, 0.1*JKQTPSTATISTICS_PI, 1.0*JKQTPSTATISTICS_PI,"k");
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size_t columnK2=ds->addLinearColumn(9, 1.1*JKQTPSTATISTICS_PI, 2.0*JKQTPSTATISTICS_PI,"k2");
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size_t columnK3=ds->addLinearColumn(9, 2.1*JKQTPSTATISTICS_PI, 3.0*JKQTPSTATISTICS_PI,"k2");
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size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return sin(x); }, "v");
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size_t columnV2=ds->addColumnCalculatedFromColumn(columnK2, [](double x) { return -sin(x); }, "v2");
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size_t columnV3=ds->addColumnCalculatedFromColumn(columnK3, [](double x) { return sin(x); }, "v3");
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size_t columnE=ds->addColumnCalculatedFromColumn(columnV, [](double x) { return 0.2*x; }, "error");
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size_t columnE2=ds->addColumnCalculatedFromColumn(columnV2, [](double x) { return 0.2*x; }, "error");
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size_t columnE3=ds->addColumnCalculatedFromColumn(columnV3, [](double x) { return 0.2*x; }, "error");
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// 3. create a graph in the plot, which plots the dataset with symmetric:
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JKQTPFilledCurveXErrorGraph* graph1=new JKQTPFilledCurveXErrorGraph(&plot);
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graph1->setKeyColumn(columnK);
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graph1->setValueColumn(columnV);
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graph1->setValueErrorColumn(columnE);
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// set error indicator style
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graph1->setValueErrorStyle(JKQTPErrorBars);
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graph1->setTitle(QObject::tr("JKQTPErrorBars"));
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plot.addGraph(graph1);
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// 4. create a second graph in the plot, which plots the second dataset with outer error bars only:
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JKQTPFilledCurveXErrorGraph* graph2=new JKQTPFilledCurveXErrorGraph(&plot);
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graph2->setKeyColumn(columnK2);
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graph2->setValueColumn(columnV2);
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graph2->setValueErrorColumn(columnE2);
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// set error indicator style
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graph2->setValueErrorStyle(JKQTPErrorPolygons);
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graph2->setTitle(QObject::tr("JKQTPErrorPolygons"));
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plot.addGraph(graph2);
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// 5. create a third graph in the plot, which plots the second dataset with outer error bars only:
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JKQTPFilledCurveXErrorGraph* graph3=new JKQTPFilledCurveXErrorGraph(&plot);
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graph3->setKeyColumn(columnK3);
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graph3->setValueColumn(columnV3);
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graph3->setValueErrorColumn(columnE3);
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// set error indicator style
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graph3->setValueErrorStyle(JKQTPErrorLines);
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graph3->setTitle(QObject::tr("JKQTPErrorLines"));
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plot.addGraph(graph3);
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// 6 autoscale the plot so the graph is contained
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plot.zoomToFit();
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// 7. show plotter and make it a decent size
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plot.getPlotter()->setKeyPosition(JKQTPKeyInsideBottomLeft);
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plot.setWindowTitle(title);
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plot.show();
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plot.resize(400,400);
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```
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The result looks like this:
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In order to draw horizontal error bars, you have to use `JKQTPFilledCurveYErrorGraph` instead of `JKQTPFilledCurveXErrorGraph`:
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