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

[menator01]

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()