Call fuction from matplotlib-button in Python

Question

I would like to call a function by pressing a matplotlib-button.

Right now, following approach works:

1. Run script
2. Press start-button in diagram window => cond=True
3. execute function in console by typing: plot_data()

The code looks similar to this,

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

#---Create BUTTON---
axButton1 = plt.axes([0.1,0.05,0.05,0.05]) #left,bottom, width, height
btn1 = Button(axButton1,"Start")

def start(event):
    global cond
    cond = True
    print(cond)
btn1.on_clicked(start)

#---Setting empty list---
t = np.array([0])
data = np.array([0])
cond = False

#---Plotting REAL TIME data---
def plot_data():
    global cond, t, data
    if (cond == True):
        #SOMETHING WILL BE EXECUTED

However, I would like to execute the function when pressing the start button and not write the command into the console again separately. I tried to call the function "plot_data()" from the function which acess the start-button,

def start(event):
    global cond
    cond = True
    print(cond)
    plot_data()
btn1.on_clicked(start)

This however does not work. Any idea what I could try?

Answer 1

Following can be your solution

import matplotlib.pylab as plt
from matplotlib.widgets import Button

fig, ax = plt.subplots()
x = [i for i in range(10)]
y = [i for i in range(10)]
axnext = plt.axes([0.81, 0.05, 0.1, 0.075])
bnext = Button(axnext, 'PLOT')

(xm, ym), (xM, yM) = bnext.label.clipbox.get_points()


def on_button_clicked(event):
    global x,y
    ax.plot(x,y)
    print(event)


bnext.on_clicked(on_button_clicked)
plt.show()

Paste above code in main.py and run python main.py.

IF YOU ARE USING JUPYTER NOTEBOOK USE BELOW

%matplotlib inline

from matplotlib.pyplot import *
import ipywidgets

button = ipywidgets.Button(description="Plot")
out = ipywidgets.Output()
x = [i for i in range(10)]
y = [i for i in range(10)]

def on_button_clicked(b):
    with out:
        plot(x,y)
        show()

button.on_click(on_button_clicked)

display(button)
out