How to instantly update the plot by getting values from a Scale widget?

[OLE]

Maybe this will get you started. I've not ever worked with matplotlib or numpy but, anyway, here's my attempt

import tkinter as tk
import numpy as np
from matplotlib.figure import Figure
from matplotlib import cm
from matplotlib.colors import ListedColormap
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

np.random.seed(2)

def plot(var, window):
	num = list(np.random.randint(low=1, high=10, size=120))
	nx, ny = 3, 4
	reshaped = np.array(num).reshape(10, nx*ny)
	layer = reshaped[var-1:var, :]
	layer = layer.reshape(nx, ny)
	x, y = np.mgrid[slice(0, nx+1, 1), slice(0, ny+1, 1)]

	figure = Figure(figsize=(4, 4))
	ax = figure.add_subplot(111)
	col_type = cm.get_cmap('rainbow', 256)
	newcolors = col_type(np.linspace(0, 1, 1000))
	white = np.array([1, 1, 1, 1])
	newcolors[:1, :] = white
	newcmap = ListedColormap(newcolors)

	c = ax.pcolormesh(x, y, layer, cmap=newcmap, edgecolor='lightgray', linewidth=0.003)
	ax.figure.colorbar(c)

	canvas = FigureCanvasTkAgg(figure, window)
	canvas.draw()
	canvas.get_tk_widget().pack()


class Window:
    def __init__(self, parent):
        self.slidervar = tk.IntVar()
        self.slider = tk.Scale(parent, from_=1, to=10, orient='horizontal')
        self.slider['variable'] = self.slidervar
        self.slider.pack()

        self.button = tk.Button(parent)
        self.button['text'] = 'Open Window'
        self.button.pack()


class TopWindow:
    def __init__(self):
        self.window = tk.Toplevel(None)
        self.window.geometry('+500+300')
        self.label = tk.Label(self.window)
        self.label.pack()

class Controller:
    def __init__(self, window):
        self.window = window

        self.window.button['command'] = self.openwindow
        self.window.slider['command'] = self.update

    def openwindow(self):
        self.topwindow = TopWindow()
        plot(self.window.slidervar.get(), self.topwindow.window)

    def update(self, event):
        plot(self.window.slidervar.get(), self.topwindow.window)

if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('200x200+250+250')
    Controller(Window(root))
    root.mainloop()

Thanks for your solution. The reason I am confused a little bit, is that this problem is a small example of my bigger code. Some of the parameters in the plot() are called from other classes, and my class's structure is a little bit different than the one you wrote. Should the plot function be always out of the classes or it can be considered within a class?