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121 lines
6.6 KiB
Markdown
121 lines
6.6 KiB
Markdown
# Example (JKQTPlotter): Different Types of Errorindicators {#JKQTPlotterErrorBarStyles}
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This project (see `./examples/errorbarstyles/`) simply creates a JKQTPlotter widget (as a new window) and adds several curves show-casing different styles of error indicators. Data is initialized from two QVector<double> objects.
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[JKQTPlotterBasicJKQTPDatastoreStatisticsGroupedStat]: @ref JKQTPlotterBasicJKQTPDatastoreStatisticsGroupedStat "1-Dimensional Group Statistics with JKQTPDatastore"
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[statisticslibrary]: @ref jkqtptools_math_statistics "JKQTPlotter Statistics Library"
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***Note:*** This examples explains how to plot graphs with error indicators, when the data has already been calculated. The tutorial [JKQTPlotterBasicJKQTPDatastoreStatisticsGroupedStat] explains one way how to use the [statisticslibrary] in order to calculate the errors from data.
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The source code of the main application can be found in [`errorbarstyles.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/errorbarstyles/errorbarstyles.cpp).
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First some data is added to the internal datastore (mostly, like explained in several other examples, like e.g. [Line Graph with Different Symbols and Line Styles](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/symbols_and_styles)). The (in a loop) several graphs are added, each with a distinct style for its error indicators:
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```.cpp
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// 3. now we make several plots with different error styles
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// for that we iterate over every style from the vector errorStyles
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// the array showXandYError indicates whether we want x- and y-error
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// for a style for all stywhere this is false, only y-error-indicators
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// are shown
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QVector<JKQTPErrorPlotstyle> errorStyles {JKQTPNoError, JKQTPErrorBars, JKQTPErrorSimpleBars, JKQTPErrorLines, JKQTPErrorPolygons, JKQTPErrorBoxes, JKQTPErrorEllipses, JKQTPErrorBarsPolygons, JKQTPErrorBarsLines, JKQTPErrorSimpleBarsLines, JKQTPErrorSimpleBarsPolygons };
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QVector<bool> showXandYError { false , true , true , false , false , true , true , false , false , false , false };
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for (int errorID=0; errorID<errorStyles.size(); errorID++) {
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// generate some plot data
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QVector<double> Y;
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for (auto& xx: X) {
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Y<<xx*0.5+static_cast<double>(errorID)*2.5;
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}
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// create a graph object
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JKQTPXYLineErrorGraph* graph=new JKQTPXYLineErrorGraph(&plot);
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// copy data into datastore and immediately set the yColumn
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graph->setXColumn(columnX);
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graph->setYColumn(ds->addCopiedColumn(Y, "y"+QString::number(errorID)));
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graph->setXErrorColumn(columnXError);
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graph->setYErrorColumn(columnYError);
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// set error style, for the y-axis
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graph->setYErrorStyle(errorStyles[errorID]);
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// no error indicators for the x-values
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graph->setXErrorStyle(JKQTPNoError);
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// ... unless: for some error styles we want error in both directions
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if (showXandYError[errorID]) {
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graph->setXErrorStyle(errorStyles[errorID]);
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graph->setDrawLine(false);
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}
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// make error indicator 30% transparent
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QColor c=graph->getErrorFillColor();
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c.setAlphaF(0.3);
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graph->setErrorFillColor(c);
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// set error indicator line width
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graph->setErrorLineWidth(1);
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// set length of small bars at the end of error bars
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graph->setErrorBarCapSize(15);
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// set symbol (cross/X) + pen style (and color)dashed)
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graph->setSymbolType(JKQTPCross);
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graph->setLineStyle(Qt::DashLine);
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// set symbol size
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graph->setSymbolSize(5);
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// set width of symbol lines
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graph->setSymbolLineWidth(1);
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// set width of graph line
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graph->setLineWidth(1);
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// graph title is made from symbol+errorStylestyle, we use the LaTeX instruction \verb around the
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// result of JKQTPErrorPlotstyle2String(), because it contains underscores that would otherwise
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// lead to lower-case letter, which we don't want
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graph->setTitle("\\verb{"+JKQTPErrorPlotstyle2String(errorStyles[errorID])+"}");
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// add the graph to the plot, so it is actually displayed
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plot.addGraph(graph);
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}
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```
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The error styles are set in these lines:
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```.cpp
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// set error style, for the y-axis
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graph->setYErrorStyle(errorStyles[errorID]);
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// no error indicators for the x-values
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graph->setXErrorStyle(errorStyles[errorID]);
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```
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There are several variables that can be used to further style the error indicator, like:
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```.cpp
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// make error indicator 30% transparent
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QColor c=graph->getErrorFillColor();
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c.setAlphaF(0.3);
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graph->setErrorFillColor(c);
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// set error indicator line width
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graph->setErrorLineWidth(1);
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// set length of small bars at the end of error bars
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graph->setErrorBarCapSize(15);
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```
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There are more properties that you can find in the documentation of the mix-in classes `JKQTPXYGraphErrors`, `JKQTPXGraphErrors`, `JKQTPYGraphErrors`, `JKQTPGraphErrors`.
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In addition the plot key is moved outside the pot and the grid in the plot is switched off:
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```.cpp
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// 6. change locaion of key (outside top-right)
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plot.getPlotter()->setKeyPosition(JKQTPKeyOutsideRightTop);
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// ... and switch off the grid
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plot.getXAxis()->setDrawGrid(false);
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plot.getXAxis()->setDrawMinorGrid(false);
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plot.getYAxis()->setDrawGrid(false);
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plot.getYAxis()->setDrawMinorGrid(false);
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```
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The result looks like this:
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Error bars are implemented in the mixin-classes `JKQTPXYGraphErrors`, `JKQTPXGraphErrors` and `JKQTPYGraphErrors` that are all derived from `JKQTPGraphErrors`. With these it is simple to add error indicators to several different plot styles. Usually you can recognize these by looking at the class name, e.g. `JKQTPXYLineGraph` is a simple line+symbol graph, and `JKQTPXYLineErrorGraph` is the same with error indictaors (see above). There are also several other plots with error indicators:
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- `JKQTPBarVerticalErrorGraph` for barcharts with errors:<br>
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- `JKQTPImpulsesVerticalGraph` for impulse/candle-stick charts with errors:<br>
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- `JKQTPFilledCurveXErrorGraph` for filled curves with errors:<br>
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.
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