why matplotlib Button not work with pyqt5? - matplotlib

Question

I now want to use the Custom Button function of matplotlib, refer to this document: https://matplotlib.org/stable/gallery/widgets/buttons.html, it works quite well.
But when I want to combine it with PyQt5, I first create a main window with a button in it. When the button is clicked, a plot will pop up, but the button in the plot loses its response.
code show as below:
import sys
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.widgets import Button
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QApplication, QPushButton, QWidget
class Index:
ind = 0
def __init__(self, l, freqs):
self.l = l
self.freqs = freqs
def next(self, event):
self.ind += 1
i = self.ind % len(self.freqs)
ydata = np.sin(2 * np.pi * self.freqs[i] * t)
self.l.set_ydata(ydata)
plt.draw()
def prev(self, event):
self.ind -= 1
i = self.ind % len(self.freqs)
ydata = np.sin(2 * np.pi * self.freqs[i] * t)
self.l.set_ydata(ydata)
plt.draw()
class App(QWidget):
def __init__(self):
super().__init__()
self.title = 'PyQt5 button - pythonspot.com'
self.left = 10
self.top = 10
self.width = 320
self.height = 200
self.initUI()
def initUI(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
button = QPushButton('PyQt5 button', self)
button.setToolTip('This is an example button')
button.move(100, 70)
button.clicked.connect(self.on_click)
self.show()
#pyqtSlot()
def on_click(self):
freqs = np.arange(2, 20, 3)
fig, ax = plt.subplots()
fig.subplots_adjust(bottom=0.2)
t = np.arange(0.0, 1.0, 0.001)
s = np.sin(2 * np.pi * freqs[0] * t)
l, = ax.plot(t, s, lw=2)
callback = Index(l, freqs)
axprev = fig.add_axes([0.7, 0.05, 0.1, 0.075])
axnext = fig.add_axes([0.81, 0.05, 0.1, 0.075])
bnext = Button(axnext, 'Next')
bnext.on_clicked(callback.next)
bprev = Button(axprev, 'Previous')
bprev.on_clicked(callback.prev)
plt.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = App()
sys.exit(app.exec_())
I want to know why?
In this question:
matplotlib event doesn't work when I use button clicked connect in pyqt5, I see that it seems to define a window myself , and then embed matplotlib, but I don't understand why
Is there a document that says we must do this?
I tried Macos, linux, windows, it works under macos, but the button doesn't respond under linux and windows.
I suspect it has something to do with QCoreApplication::exec: The event loop is already running, but I don't understand why the qt problem affects matplotlib. Is the signal of matplotlib registered to pyqt5?

Answer 1

Yes, Yes, You need not to a PlotEx, ref to Why aren't the matplotlib checkboxes working in pyQt5?
I understood that is because the button is local var, I need a more big scope.
the right code is :
import sys
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.widgets import Button
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QApplication, QPushButton, QWidget
class Index:
ind = 0
def __init__(self, l, freqs, t):
self.l = l
self.freqs = freqs
self.t = t
def next(self, event):
self.ind += 1
i = self.ind % len(self.freqs)
ydata = np.sin(2 * np.pi * self.freqs[i] * self.t)
self.l.set_ydata(ydata)
plt.draw()
def prev(self, event):
self.ind -= 1
i = self.ind % len(self.freqs)
ydata = np.sin(2 * np.pi * self.freqs[i] * self.t)
self.l.set_ydata(ydata)
plt.draw()
class App(QWidget):
def __init__(self):
super().__init__()
self.title = 'PyQt5 button - pythonspot.com'
self.left = 10
self.top = 10
self.width = 320
self.height = 200
self.initUI()
def initUI(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
button = QPushButton('PyQt5 button', self)
button.setToolTip('This is an example button')
button.move(100, 70)
button.clicked.connect(self.on_click)
self.show()
#pyqtSlot()
def on_click(self):
freqs = np.arange(2, 20, 3)
fig, ax = plt.subplots()
fig.subplots_adjust(bottom=0.2)
t = np.arange(0.0, 1.0, 0.001)
s = np.sin(2 * np.pi * freqs[0] * t)
l, = ax.plot(t, s, lw=2)
callback = Index(l, freqs, t)
axprev = fig.add_axes([0.7, 0.05, 0.1, 0.075])
axnext = fig.add_axes([0.81, 0.05, 0.1, 0.075])
bnext = Button(axnext, 'Next')
bnext.on_clicked(callback.next)
bprev = Button(axprev, 'Previous')
bprev.on_clicked(callback.prev)
plt.bnext = bnext
plt.bprev = bprev
plt.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = App()
sys.exit(app.exec_())
The difference is add (and fix some bugs):
plt.bnext = bnext
plt.bprev = bprev