[FIXED] Python: Matplotlib Button not working (in the second plot)

Issue

I'm using a matplotlib button to create another plot with a button. However, the second button in the second plot does not work. Could anyone take a look at my code and give me some help?

import numpy as np
import matplotlib
import matplotlib.pyplot as plt
import tkinter as tk
from matplotlib.widgets import Button

def next1(event):
    print("you clicked here")

def next0(event):

    # plt.close('all')
    fig, ax = plt.subplots()
    rects = ax.bar(range(10), 20*np.random.rand(10))

    axnext1 = plt.axes([0.11, 0.05, 0.05, 0.0375])
    bnext1 = Button(axnext1, 'Next2')
    print(bnext1.label)
    bnext1.on_clicked(next1)
    plt.show()

fig, ax = plt.subplots()
rects = ax.bar(range(10), 20*np.random.rand(10))

axnext0 = plt.axes([0.11, 0.05, 0.05, 0.0375])
bnext0 = Button(axnext0, 'Next1')
print(bnext0.label)
bnext0.on_clicked(next0)

plt.show()

This figure shows the problem I had. The second figure is created by the button in the first image. While the button in the second figure does not work.

Solution

It seems problem is because you assign second button to local variable (inside function) and python deletes this object when it finishes function. Button has to be assigned to global variable - to keep it after finishing function.

def next0(event):
    global bnext1

    # ... code ...

---

BTW:

After clicking first button it shows me information (not erorr message)

QCoreApplication::exec: The event loop is already running 

because second window tries to create new event loop but event loop already exists - created by first window.

To resolve this problem you can run second window in non-blocking mode.

def next0(event):
    global bnext1

    # ... code ...

    plt.show(block=False)

Answered By - furas