使用对数数值轴

显示一条折线图的截图，其中y轴的数值采用对数刻度

创建一个 QLineSeries 实例，并向其中添加一些数据。

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);

要在图表上展示数据，我们需要一个 QChart 实例。将数据系列添加到该实例中，隐藏图例并设置图表标题。

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

创建坐标轴。将其添加到图表中，并关联到数据系列。

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);

然后创建一个以 QChart 为参数的 QChartView 对象。

createDefaultChartView(chart);

图表现已准备就绪，可以显示了。

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