- Qt 6.12
- Qt Charts
- Using Logarithmic Value Axes
- Qt Charts | Commercial or GPLv3

# Using Logarithmic Value Axes

Note: This is part of the Charts with Widgets Gallery example.

Create a QLineSeries instance and add some data to it.

     auto series = new QLineSeries;
     *series << QPointF(1.0, 1.0) << QPointF(2.0, 73.0) << QPointF(3.0, 268.0) << QPointF(4.0, 17.0)
             << QPointF(5.0, 4325.0) << QPointF(6.0, 723.0);

To present the data on the chart we need a QChart instance. Add the series to it, hide the legend and set the title of the chart.

     auto chart = new QChart;
     chart->addSeries(series);
     chart->legend()->hide();
     chart->setTitle("Logarithmic Axis");

Create the axes. Add them to the chart and attach to the series.

     auto axisX = new QValueAxis;
     axisX->setTitleText("Data point");
     axisX->setLabelFormat("%i");
     axisX->setTickCount(series->count());
     chart->addAxis(axisX, Qt::AlignBottom);
     series->attachAxis(axisX);

     auto axisY = new QLogValueAxis;
     axisY->setTitleText("Values");
     axisY->setLabelFormat("%g");
     axisY->setBase(8.0);
     axisY->setMinorTickCount(-1);
     chart->addAxis(axisY, Qt::AlignLeft);
     series->attachAxis(axisY);

Then create a QChartView object with QChart as a parameter.

     createDefaultChartView(chart);

The chart is ready to be shown.