How to update matplotlib embedded into tkinter? - python-3.x

Question

The problem is that I want to draw a plot by clicking on a button but it doesn't work. However, when I call draw from __init__, the plot appears on the screen.
Plotter.py
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from matplotlib.figure import Figure
class Plotter(FigureCanvasTkAgg):
def __init__(self, master):
self.figure = Figure(dpi=100)
super().__init__(self.figure, master=master)
self.axes = self.figure.add_subplot(111)
self.get_tk_widget().grid(column=0, row=0, sticky='nsew')
def draw(self):
self.axes.clear()
x_list = [x for x in range(0, 100)]
y_list = [x^3 for x in x_list]
self.axes.plot(x_list, y_list, color='y')
MainApplication.py
from tkinter import ttk
import tkinter as tk
import plotter
class MainApplication(ttk.Frame):
def __init__(self, master, *args, **kwargs):
super().__init__(root)
self.grid(column=0, row=0, sticky='nsew')
frame = ttk.Frame(self, borderwidth=8)
frame.grid(column=0, row=0, sticky='nsew')
frame.rowconfigure(0, weight=1)
notes = ttk.Notebook(frame)
notes.grid(column=0, row=0, sticky='nsew')
notes.rowconfigure(0, weight=1)
page = ttk.Frame(notes)
notes.add(page, text='Picture')
plot = plotter.Plotter(page)
# plot.draw() # This call updates the plot
input_frame = ttk.Frame(self)
input_frame.grid(column=1, row=0, sticky='nsew')
# this binding doesn't update the plot
button = ttk.Button(input_frame, text='Plot', \
command=lambda: plot.draw())
button.grid(column=0, row=4, columnspan=2, sticky='ew')
root = tk.Tk()
MainApplication(root)
root.mainloop()

Answer 1

Personally I would write this up in a single class so that we can use class attributes and methods to control everything with ease. Also you do not need a lambda here. Just save the reference to the command button and not a lambda call. That said you were also overwriting the draw method of FigureCanvasTkAgg so change the draw() method to something else.
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from matplotlib.figure import Figure
from tkinter import ttk
import tkinter as tk
class MainApplication(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
notes = ttk.Notebook(self)
notes.grid(column=0, row=0, sticky='nsew')
notes.rowconfigure(0, weight=1)
self.page = ttk.Frame(notes)
notes.add(self.page, text='Picture')
self.plotter()
input_frame = ttk.Frame(self)
input_frame.grid(column=1, row=0, sticky='nsew')
button = ttk.Button(input_frame, text='Plot', command=self.new_draw)
button.grid(column=0, row=4, columnspan=2, sticky='ew')
def plotter(self):
self.figure = Figure(dpi=100)
self.plot_canvas = FigureCanvasTkAgg(self.figure, self.page)
self.axes = self.figure.add_subplot(111)
self.plot_canvas.get_tk_widget().grid(column=0, row=0, sticky='nsew')
def new_draw(self):
self.axes.clear()
x_list = [x for x in range(0, 100)]
y_list = [x^3 for x in x_list]
self.axes.plot(x_list, y_list, color='y')
self.plot_canvas.draw_idle()
MainApplication().mainloop()

Answer 2

You overwrote the canvas' draw method without reimplementing it. But since you do not want to update your plot on every draw-event anyways, I'd suggest to call the method to update the plot differently, e.g. draw_lists. Inside draw_lists you would then need to call the draw method of the canvas (or in this case better draw_idle).
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from matplotlib.figure import Figure
class Plotter(FigureCanvasTkAgg):
def __init__(self, master):
self.figure = Figure(dpi=100)
super().__init__(self.figure, master=master)
self.axes = self.figure.add_subplot(111)
self.get_tk_widget().grid(column=0, row=0, sticky='nsew')
def draw_lists(self):
self.axes.clear()
x_list = [x for x in range(0, 100)]
y_list = [x^3 for x in x_list]
self.axes.plot(x_list, y_list, color='y')
self.draw_idle()
from tkinter import ttk
import tkinter as tk
class MainApplication(ttk.Frame):
def __init__(self, master, *args, **kwargs):
super().__init__(root)
self.grid(column=0, row=0, sticky='nsew')
frame = ttk.Frame(self, borderwidth=8)
frame.grid(column=0, row=0, sticky='nsew')
frame.rowconfigure(0, weight=1)
notes = ttk.Notebook(frame)
notes.grid(column=0, row=0, sticky='nsew')
notes.rowconfigure(0, weight=1)
page = ttk.Frame(notes)
notes.add(page, text='Picture')
plot = Plotter(page)
input_frame = ttk.Frame(self)
input_frame.grid(column=1, row=0, sticky='nsew')
# this binding doesn't update the plot
button = ttk.Button(input_frame, text='Plot', \
command=lambda: plot.draw_lists())
button.grid(column=0, row=4, columnspan=2, sticky='ew')
root = tk.Tk()
MainApplication(root)
root.mainloop()