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74 lines
2.7 KiB
Markdown
74 lines
2.7 KiB
Markdown
# Example (JKQTPlotter): Simple impulse plots {#JKQTPlotterImpulsePlots}
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This project (see `./examples/impulsesplot/`) simply creates a JKQTPlotter widget (as a new window) and adds a single impulse graph.
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The source code of the main application is (see [`impulsesplot.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/impulsesplot/impulsesplot.cpp).
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First data for a curve is calculated and stored in `QVector<double>`:
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```.cpp
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QVector<double> X, Y;
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for (int i=0; i<Ndata; i++) {
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const double xx=double(i)/double(Ndata)*6.0*M_PI;
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X << xx;
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Y << cos(xx)*exp(-xx/10.0);
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}
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```
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... and finally the data is copied into the datastore
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```.cpp
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size_t columnX=ds->addCopiedColumn(X, "x");
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size_t columnY=ds->addCopiedColumn(Y, "y");
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```
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Now an impulse graph object is generated and added to the plot:
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```.cpp
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JKQTPImpulsesVerticalGraph* graph=new JKQTPImpulsesVerticalGraph(&plot);
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graph->setXColumn(columnX);
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graph->setYColumn(columnY);
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graph->setLineWidth(2);
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graph->setColor(QColor("red"));
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graph->setTitle(QObject::tr("$\\cos(x)\\cdot\\exp(-x/10)$"));
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plot.addGraph(graph);
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```
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The result looks like this:
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There is an alternative class `JKQTPImpulsesHorizontalGraph` which draws horizontal impulse plots:
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```.cpp
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JKQTPImpulsesHorizontalGraph* graph=new JKQTPImpulsesHorizontalGraph(&plot);
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graph->setYColumn(columnX);
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graph->setXColumn(columnY);
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graph->setLineWidth(2);
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graph->setColor(QColor("blue"));
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graph->setTitle(QObject::tr("$\\cos(x)\\cdot\\exp(-x/10)$"));
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```
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This code snippet results in a plot like this:
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The classes `JKQTPImpulsesVerticalGraph` and `JKQTPImpulsesHorizontalGraph` also provide the ability to draw a symbol at the end of the impulse, e.g. using this code:
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```.cpp
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graph->setDrawSymbols(true);
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graph->setSymbolType(JKQTPGraphSymbols::JKQTPFilledStar);
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```
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This code snippet results in a plot like this:
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Finally you can move the baseline (i.e. the level, where the impulses start, which is typically x=0 or y=0) in the classes `JKQTPImpulsesVerticalGraph` and `JKQTPImpulsesHorizontalGraph`:
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```.cpp
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graph->setBaseline(0.25);
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```
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This code snippet results in a plot like this:
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