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54 lines
2.9 KiB
Markdown
54 lines
2.9 KiB
Markdown
# Example (JKQTPlotter): Step Line Plots in Different Styles {#JKQTPlotterStepPlot}
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This project (see `./examples/simpletest_stepplots/`) 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.
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The source code of the main application can be found in [`jkqtplotter_simpletest_stepplots.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/simpletest_stepplots/jkqtplotter_simpletest_stepplots.cpp). For the most part, several datasets of cosine-curves are generated. then thrre tuples of graphs are added: One of type `JKQTPXYLineGraph`, which simply indicates the location of the actual datapoints. the second is of type `JKQTPStepHorizontalGraph`, which adds the step-graph to the plot:
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```.cpp
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// 3 now we make several plots with different step styles, each one also contains a
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// symbol plot indicating the location of the datapoints themselves
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JKQTPStepHorizontalGraph* graph;
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JKQTPXYLineGraph* graphL;
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//-- JKQTPStepLeft ----------------------------------------------------------------------------------------
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graph=new JKQTPStepHorizontalGraph(&plot);
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graphL=new JKQTPXYLineGraph(&plot);
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// set data for both graphs
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graph->setXColumn(columnX); graphL->setXColumn(graph->getXColumn());
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graph->setYColumn(columnY1); graphL->setYColumn(graph->getYColumn());
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// set step style
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graph->setStepType(JKQTPStepLeft);
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graph->setLineWidth(1);
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graph->setFillCurve(true);
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graph->setDrawLine(true);
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graph->setTitle("JKQTPStepLeft, filled");
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```
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Note that you can configure the step type (left/center/right by `graph->setStepType(JKQTPStepLeft)`. With `graph->setFillCurve(true)` you can draw the curve filled until the y=0-axis and with `graph->setDrawLine(true)` you can switch the line along the values on and off (e.g. to only have the filled area, but no line).
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Finally the `JKQTPXYLineGraph` is configured:
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```.cpp
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// set symbol + pen style and color for the added circles, copy color
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graphL->setSymbol(JKQTPGraphSymbols::JKQTPCircle);
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graphL->setDrawLine(false);
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graphL->setSymbolSize(9);
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graphL->setSymbolWidth(1);
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graphL->setColor(graph->getColor());
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```
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... and all graphs are added to the plot:
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```.cpp
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// add the graphs to the plot, so it is actually displayed
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plot.addGraph(graph);
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plot.addGraph(graphL);
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```
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In addition to the symbol type and line style, you can also alter the size of the symbols (`graph->setSymbolSize(14)`), the line-width used to draw them (`graph->setSymbolWidth(1.5)`) and the line width of the graph line (`graph->setLineWidth(1)`). If you want to switch off the line altogether, use `graph->setDrawLine(false`.
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The result looks like this:
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