How to update matplotlib embedded into tkinter?

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()

Mike - SMT · Accepted Answer · 2018-11-05 14:44:15Z

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()

ImportanceOfBeingErnest · Accepted Answer · 2018-11-05 14:21:33Z

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()

I would change command=lambda: plot.draw_lists() to command= plot.draw_lists.

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