added example for log axes

README.md

@@ -18,7 +18,8 @@ All test-projects are Qt-projects that use qmake to build. You can load them int
 | Screenshot    | Description   | Notes         |
 |:-------------:| ------------- | ------------- |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest1_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest) | [Very Basic Example (Line Graph)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest) | `JKQTPxyLineGraph`<br/>C-style arrays of data |
-| [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_symbols_and_styles_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | [Line Graph with Different Symbols and Line Styles](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | `JKQTPxyLineGraph`<br/>C++ vector of data |
+| [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_symbols_and_styles_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | [Line Graph with Different Symbols and Line Styles](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_styles) | `JKQTPxyLineGraph`<br/>C++ vector of data<br/>setting line styles and symbol styles<br/>automatic graph coloring |
+| [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_logaxes_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_logaxes) | [logarithmic axes](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_logaxes) | `JKQTPxyLineGraph` and `JKQTPgeoText`<br/>C++ vector of data<br/>logarithmic axes<br/>plot line styles<br/>internal LaTeX parser<br/>add commenting text to a graph |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_symbols_and_errors_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_errors) | [Simple Line/Symbol Graph With Errorbars](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_symbols_and_errors) | `JKQTPxyLineErrorGraph`<br/>C-style arrays of data |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtplotter_simpletest_barchart_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_barchart) | [Simple Bar Charts](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_barchart) | `JKQTPbarVerticalGraph`<br/>C-style arrays of data |
 | [![](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/JKQTPbarVerticalGraphStacked_small.png)](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_stackedbars) | [Stacked Bar Charts](https://github.com/jkriege2/JKQtPlotter/tree/master/test/jkqtplotter_simpletest_stackedbars) | `JKQTPbarVerticalStackableGraph`, `JKQTPbarHorizontalStackableGraph`<br/>C++-style vectors of data |

test/jkqtplotter_simpletest_logaxes/README.md

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

test/jkqtplotter_simpletest_logaxes/jkqtplotter_simpletest_logaxes.cpp

@@ -0,0 +1,81 @@
+#include <QApplication>
+#include "jkqtplotter/jkqtplotter.h"
+#include "jkqtplotter/jkqtpgeoelements.h"
+#include "jkqtplottertools/jkqtptools.h"
+
+#define sqr(x) ((x)*(x))
+
+int main(int argc, char* argv[])
+{
+    QApplication app(argc, argv);
+
+    // 1. create a plotter window and get a pointer to the internal datastore (for convenience)
+    JKQtPlotter plot;
+    JKQTPdatastore* ds=plot.getDatastore();
+
+    // 2. now we create data a vector of x-values for a simple plot (resonance curve with different damping value D)
+    //    see https://en.wikipedia.org/wiki/Resonance
+    QVector<double> X;
+    QVector<double> D { 0.001, 0.1, 1, 10};
+    const int Ndata=500; // number of plot points in each curve
+    for (int i=0; i<Ndata; i++) {
+        const double x=double(i)/double(Ndata)*3;
+        X<<x;
+        //Y1<<1.0/sqrt(sqr(1-sqr(x))+sqr(2*x*D1));
+    }
+    // and copy it to the datastore
+    size_t columnX=ds->addCopiedColumn(X, "x");
+
+    // 3. now we make several plots for different values of D
+    QVector<Qt::PenStyle> pens {Qt::SolidLine, Qt::DashLine, Qt::DotLine, Qt::DashDotLine, Qt::DashDotDotLine };
+    for (int id=0; id<D.size(); id++) {
+        // generate some plot data
+        QVector<double> Y;
+        for (auto& xx: X) {
+            Y<<1.0/sqrt(sqr(1-sqr(xx))+sqr(2*xx*D[id]));
+        }
+
+        JKQTPxyLineGraph* graph=new JKQTPxyLineGraph(&plot);
+
+        // copy data into datastore and immediately set the yColumn
+        graph->set_xColumn(columnX);
+        graph->set_yColumn(ds->addCopiedColumn(Y, "y"+QString::number(id)));
+
+        // don't use symbols
+        graph->set_symbol(JKQTPnoSymbol);
+        // use one of different pens
+        graph->set_style(pens[id%pens.size()]);
+        // set width of graph line
+        graph->set_lineWidth(1.5);
+
+        // graph title is made from symbol+penstyle
+        graph->set_title(QString("D=\\delta/\\omega_0=%1").arg(D[id]));
+
+        // add the graph to the plot, so it is actually displayed
+        plot.addGraph(graph);
+    }
+
+    // 4. Also we add a text-element in the plot to show the plotted function
+    //    This element (JKQTPgeoText) is taken from the set of geometric elements
+    //    and is simply parametrized by a position (1.25/10) and the text to display.
+    //    In addition you can also set the font size (here to 15)
+    plot.addGraph(new JKQTPgeoText(&plot, 1.25, 10, "\\frac{A}{A_{stat}}=\\frac{1}{\\sqrt{\\left(1-\\eta^2\\right)^2+\\left(2{\\eta}D\\right)^2}}", 15));
+    // for nicer rendering we set the fonts used by the internal LaTeX parser instance to XITS
+    //plot.get_plotter()->get_mathText()->useXITS();
+
+    // 4. set y-axis to logarithmic (x-axis would be analogous)
+    //    and set axis labels (using LaTeX notation)
+    plot.get_yAxis()->set_logAxis(true);
+    plot.get_yAxis()->set_axisLabel("Amplitude A/A_{stat}");
+    plot.get_xAxis()->set_axisLabel("relative driving frequency \\eta=\\omega/\\omega_0");
+
+
+    // 5. autoscale the plot so the graph is contained
+    plot.zoomToFit();
+
+    // 6. show plotter and make it a decent size
+    plot.show();
+    plot.resize(600,400);
+
+    return app.exec();
+}

test/jkqtplotter_simpletest_logaxes/jkqtplotter_simpletest_logaxes.pro

@@ -0,0 +1,20 @@
+# source code for this simple demo
+SOURCES = jkqtplotter_simpletest_logaxes.cpp 
+
+# configure Qt
+CONFIG += qt
+QT += core gui svg
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets printsupport
+
+# output executable name
+TARGET = jkqtplotter_simpletest_logaxes
+
+# include JKQtPlotter source code
+include(../../lib/jkqtplotter.pri)
+include(../../lib/jkqtplotterressources/math_fonts/xits.pri)
+DEFINES += AUTOLOAD_XITS_FONTS
+DEFINES += USE_XITS_FONTS
+
+# here you can activate some debug options
+#DEFINES += SHOW_JKQTPLOTTER_DEBUG
+#DEFINES += JKQTBP_AUTOTIMER