如何绘制在 x 轴上左右移动的轨迹图？

Question

我想在停车场的汽车的 x 和 y 方向绘制轨迹。

x 中的轨迹并不总是同一个方向。有时车会向左走。

这里的问题是：有时（不总是！）图形不会在 x 轴上向左移动。你可以在图像上看到两个不同的结果https://imgur.com/Z53fNkt

知道为什么吗？

左图是我所期望的。右边是相同的值，但我继续绘制数据的时间更长一些。

void TrackingResultsView::setupTrajectoryPlot()
{
QCustomPlot *customPlot = ui->qcp_trajectory;

customPlot->xAxis2->setVisible(true);
customPlot->xAxis2->setLabel("X-Position (pixel)");
customPlot->xAxis2->setRange(0, mModelPtr->frameSize().width());
customPlot->xAxis2->grid()->setVisible(true);

customPlot->xAxis->setRange(0, mModelPtr->frameSize().width());
customPlot->yAxis->setLabel("Y-Position (pixel)");
customPlot->yAxis->setRange(0, mModelPtr->frameSize().height());
customPlot->yAxis->setRangeReversed(true);

customPlot->yAxis2->setVisible(true);
customPlot->yAxis2->setRange(0, mModelPtr->frameSize().height());
customPlot->yAxis2->grid()->setVisible(true);
customPlot->yAxis2->setRangeReversed(true);
customPlot->addGraph(customPlot->xAxis2, customPlot->yAxis);

QVector<QVector<double>> data = createDataMap(mModelPtr->points());
customPlot->graph()->setData(data.at(0), data.at(1), true);

setTheme(customPlot, false);
}

谢谢

（英语不是我的第一语言）

Answer 1

QCPGraph 似乎用于每个键只有值的排序数据。从 QCustomPlot 文档来看，QCPCurve 看起来更适合绘制轨迹图（同一键的多个值）。

来自QCPCurve描述：

Unlike QCPGraph, plottables of this type may have multiple points with the same key coordinate, so their visual representation can have loops. This is realized by introducing a third coordinate t, which defines the order of the points described by the other two coordinates x and y.

Answer 2

这是我在 olivier 帮助下的新代码。它的工作！

QCustomPlot *customPlot = ui->qcp_trajectory;

customPlot->xAxis2->setVisible(true);
customPlot->xAxis2->setLabel("X-Position (pixel)");
customPlot->xAxis2->setRange(0, mModelPtr->frameSize().width());
customPlot->xAxis2->grid()->setVisible(true);

customPlot->xAxis->setRange(0, mModelPtr->frameSize().width());
customPlot->yAxis->setLabel("Y-Position (pixel)");
customPlot->yAxis->setRange(0, mModelPtr->frameSize().height());
customPlot->yAxis->setRangeReversed(true);

customPlot->yAxis2->setVisible(true);
customPlot->yAxis2->setRange(0, mModelPtr->frameSize().height());
customPlot->yAxis2->grid()->setVisible(true);
customPlot->yAxis2->setRangeReversed(true);

customPlot->addGraph(customPlot->xAxis2, customPlot->yAxis);

// create empty curve objects:
QCPCurve *trajectory = new QCPCurve(customPlot->xAxis2, customPlot->yAxis);

// generate the curve data points:
const int pointCount = mModelPtr->points().size();
QVector<QCPCurveData> datatrajectory(pointCount);
QVector<QVector<double>> data = createDataMap(mModelPtr->points());

for (int i = 0; i < pointCount ; ++i)
{
    datatrajectory[i] = QCPCurveData(i, data.at(0).at(i), data.at(1).at(i));

}

trajectory->data()->set(datatrajectory, true);
setTheme(customPlot, false);

如何绘制在 x 轴上左右移动的轨迹图？

How to draw graph for a trajectory which goes left and right in x axis?

c++

qcustomplot