Get data point where mouse is

[Bobby Lucero]

The image above is an example of what i'd like to do

Hello, i'd like to get the data at a certain point where my mouse is hovered over the graph. I'm trying to get the circle to hover over the data point where the mouse is, as demonstrated in the screenshot. I already have code to track the mouses position, I just have no idea to get the actual plot data where the mouse is.

Any help would be greatly appreciated.

[Patrick]

Hi,

Still needs a bit of polish, but how about:

from PyQt5 import QtWidgets
import pyqtgraph as pg
import numpy as np

class TestPlot(pg.GraphicsLayoutWidget):

    def __init__(self):
        super().__init__()
        self.curveData = np.random.rand(200)
        self.plotItem = self.addPlot()
        self.plotDataItem = self.plotItem.plot(self.curveData)
        self.plotHighlight = pg.ScatterPlotItem(size=10, pen={"color": "#8080ff"}, brush="#000000")
        self.plotItem.addItem(self.plotHighlight, ignoreBounds=True)
        self.plotLabel = pg.TextItem("X", anchor=(0.5, 1.0))
        self.plotItem.addItem(self.plotLabel, ignoreBounds=True)

        self.selected_x_i = 0
        # Create the infinite line to indicate an x coordinate
        self.crosshairx = pg.InfiniteLine(angle=90, movable=False, pen={"color": "#8080ff"})
        self.plotItem.addItem(self.crosshairx, ignoreBounds=True)

        self.signalproxy = pg.SignalProxy(self.plotItem.scene().sigMouseMoved, rateLimit=60, slot=self.mouseMoved)

    def mouseMoved(self, event):
        pos = event[0]  ## using signal proxy turns original arguments into a tuple
        if self.plotItem.sceneBoundingRect().contains(pos):
            mousePoint = self.plotItem.getViewBox().mapSceneToView(pos)
            index = int(mousePoint.x())
            if (index > 0 and index < self.curveData.shape[0] and
                mousePoint.y() >= self.plotItem.getViewBox().viewRange()[1][0] and
                mousePoint.y() <= self.plotItem.getViewBox().viewRange()[1][1]):
                #self.crosshairx.label.setFormat("{:0.2f}".format(self.curveData[index]))s
                self.crosshairx.setPos(mousePoint.x())
                self.plotHighlight.setData([index], [self.curveData[index]])
                self.plotLabel.setPos(index, self.curveData[index])
                self.plotLabel.setText("{:0.2g}".format(self.curveData[index]))
            else:
                # Could proably hide the crosshair in better way...
                self.crosshairx.setPos(self.plotItem.getViewBox().viewRange()[0][0] - 1)
                self.plotHighlight.clear()
                self.plotLabel.setText("")

def main():
    import sys
    app = QtWidgets.QApplication(sys.argv)
    mainwindow = TestPlot()
    mainwindow.show()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Patrick

[Bobby Elliott]

That’s pretty much exactly what I wanted, thank you!

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