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69 lines
3.3 KiB
Markdown
69 lines
3.3 KiB
Markdown
[Back to JKQTPlotter main page](https://github.com/jkriege2/JKQtPlotter/)
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# JKQtPlotter
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## Line Graph with Logarithmic y-axis
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This project (see `./test/jkqtplotter_simpletest_logaxes/`) simply creates a JKQtPlotter widget (as a new window) and several line-graphs of different resonance curves.
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The source code of the main application can be found in [`jkqtplotter_simpletest_logaxes.cpp`](https://github.com/jkriege2/JKQtPlotter/blob/master/test/jkqtplotter_simpletest_logaxes/jkqtplotter_simpletest_logaxes.cpp). Mainly several graphs are generated in a loop and then different line styles are applied to the graphs (set by ``graph->set_style()`). The colors are set automtically from an internal default palette. The main loop looks like this:
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```c++
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QVector<Qt::PenStyle> pens {Qt::SolidLine, Qt::DashLine, Qt::DotLine, Qt::DashDotLine, Qt::DashDotDotLine };
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for (int id=0; id<D.size(); id++) {
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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<<1.0/sqrt(sqr(1-sqr(xx))+sqr(2*xx*D[id]));
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}
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JKQTPxyLineGraph* graph=new JKQTPxyLineGraph(&plot);
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// copy data into datastore and immediately set the yColumn
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graph->set_xColumn(columnX);
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graph->set_yColumn(ds->addCopiedColumn(Y, "y"+QString::number(id)));
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// don't use symbols
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graph->set_symbol(JKQTPnoSymbol);
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// use one of different pens
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graph->set_style(pens[id%pens.size()]);
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// set width of graph line
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graph->set_lineWidth(1.5);
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// graph title is made from symbol+penstyle
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graph->set_title(QString("D=\\delta/\\omega_0=%1").arg(D[id]));
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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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Then a `JKQTPgeoText` is added to the graph, which shows the function plotted in the plot:
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```c++
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// 4. Also we add a text-element in the plot to show the plotted function
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// This element (JKQTPgeoText) is taken from the set of geometric elements
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// and is simply parametrized by a position (1.8/10) and the text to display.
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// In addition you can also set the font size (here to 15)
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plot.addGraph(new JKQTPgeoText(&plot, 1.8, 10, "\\frac{A}{A_{stat}}=\\frac{1}{\\sqrt{\\left(1-\\eta^2\\right)^2+\\left(2{\\eta}D\\right)^2}}", 15));
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// for nicer rendering we set the fonts used by the internal LaTeX parser instance to XITS
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plot.get_plotter()->get_mathText()->useXITS();
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```
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Finally the y-axis is switched to logarithmic scaling and the axis labels are set:
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```c++
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// 4. set y-axis to logarithmic (x-axis would be analogous)
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// and set axis labels (using LaTeX notation)
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plot.get_yAxis()->set_logAxis(true);
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plot.get_yAxis()->set_axisLabel("Amplitude A/A_{stat}");
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plot.get_xAxis()->set_axisLabel("relative driving frequency \\eta=\\omega/\\omega_0");
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```
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The result looks like this:
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Without the logarithmic scaling we would have:
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[Back to JKQTPlotter main page](https://github.com/jkriege2/JKQtPlotter/) |