Logarithmic Axis Example#

The example shows how to use QLogValueAxis .

../_images/examples_logvalueaxis.png

Running the Example#

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Using Logarithmic Value Axes#

Create a QLineSeries instance and add some data to it.

series = 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.

chart = QChart()
chart.addSeries(series)
chart.legend().hide()
chart.setTitle("Logarithmic axis example")

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

axisX = QValueAxis()
axisX.setTitleText("Data point")
axisX.setLabelFormat("%i")
axisX.setTickCount(series.count())
chart.addAxis(axisX, Qt.AlignBottom)
series.attachAxis(axisX)
axisY = 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. Enable antialiasing to have the rendered line look nicer.

chartView = QChartView(chart)
chartView.setRenderHint(QPainter.Antialiasing)

The chart is ready to be shown.

window = QMainWindow()
window.setCentralWidget(chartView)
window.resize(800, 600)
window.show()

Example project @ code.qt.io