How to collect the axis object of the last mouse click in matplotlib canvas drawn with pyqt5?

Question

I have an interactive window and I need to know which subplot was selected during the interaction. When I was using matplotlib alone, I could use plt.connect('button_press_event', myMethod). But with pyqt5, I am importing FigureCanvasQTAgg and there is a reference to the figure itself but not an equivalent of pyplot. So, I am unable to create that reference.

Minimal reproducible example:

from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas, NavigationToolbar2QT as NavigationToolbar
import matplotlib.pyplot as plt
from matplotlib.widgets import SpanSelector
import numpy as np

# list to store the axis last used with a mouseclick
currAx = []


# detect the currently modified axis
def onClick(event):
    if event.inaxes:
        currAx[:] = [event.inaxes]


class MyWidget(QWidget):
    def __init__(self):
        super().__init__()

        self.canvas = FigureCanvas(plt.Figure())
        self.axis = self.canvas.figure.subplots(3)
        for i, ax in enumerate(self.axis):
            t = np.linspace(-i, i + 1, 100)
            ax.plot(t, np.sin(2 * np.pi * t))
        self.listOfSpans = [SpanSelector(
            ax,
            self.onselect,
            "horizontal"
        )
            for ax in self.axis]
        plt.connect('button_press_event', onClick)
        # need an equivalent of ^^ to find the axis interacted with
        self.init_ui()

    def init_ui(self):
        layout = QVBoxLayout()
        toolbar = NavigationToolbar(self.canvas, self)
        layout.addWidget(toolbar)
        layout.addWidget(self.canvas)
        self.setLayout(layout)
        self.show()

    def onselect(self, xmin, xmax):
        if xmin == xmax:
            return
        # identify the axis interacted and do something with that information
        for ax, span in zip(self.axis, self.listOfSpans):
            if ax == currAx[0]:
                print(ax)
        print(xmin, xmax)
        self.canvas.draw()


def run():
    app = QApplication([])
    mw = MyWidget()
    app.exec_()


if __name__ == '__main__':
    run()

score 0 · Accepted Answer · answered Apr 14 '22 at 01:57

Apparently, there is a method for connecting canvas as well - canvas.mpl_connect('button_press_event', onclick).

Link to the explanation: https://matplotlib.org/stable/users/explain/event_handling.html

Found the link to the explanation in this link :Control the mouse click event with a subplot rather than a figure in matplotlib.

How to collect the axis object of the last mouse click in matplotlib canvas drawn with pyqt5?

1 Answers1