Loading a matplotlib figure pickle within a tkinter GUI

[Vital-Fernandez]

Hi I am using matplotlib 2.0.0b4 in ubuntu 15.10 and I wonder if anyone could please offer me some advice on how to tackle this issue:

There are several examples on the gallery on how to embed matplotlib figures in a GUI and how to use the pickle pickle functionality however I cannot make them both work together. This is one example from matplotlib 1.5.3:

import sys
import pickle
import matplotlib
from numpy import arange, sin, pi, cos
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg
from matplotlib.backend_bases import key_press_handler
from matplotlib.figure import Figure
if sys.version_info[0] < 3:
    import Tkinter as Tk
else:
    import tkinter as Tk

def restore_from_pickle(pickle_address, fig):
    fig.clear()
    with open(pickle_address, 'rb') as fid:
        fig = pickle.load(fid)
    return

def _quit():
    root.quit()
    root.destroy()

def on_key_event(event):
    print('you pressed %s' % event.key)
    key_press_handler(event, canvas, toolbar)

matplotlib.use('TkAgg')
root = Tk.Tk()
root.wm_title("Embedding in TK")

f = Figure(figsize=(5, 4), dpi=100)
t = arange(0.0, 3.0, 0.01)

#Plot to store
a = f.add_subplot(111)
s = sin(2*pi*t)
a.plot(t, s)

#Saving to pickle
with open('figure_pickle', 'wb') as fid:
    pickle.dump(f, fid)

#Initial plot display
f.clear()
a = f.add_subplot(111)
s = cos(2*pi*t)
a.plot(t, s)

# a tk.DrawingArea
canvas = FigureCanvasTkAgg(f, master=root)
canvas.show()
canvas.get_tk_widget().pack(side=Tk.TOP, fill=Tk.BOTH, expand=1)

toolbar = NavigationToolbar2TkAgg(canvas, root)
toolbar.update()
canvas._tkcanvas.pack(side=Tk.TOP, fill=Tk.BOTH, expand=1)

canvas.mpl_connect('key_press_event', on_key_event)

button = Tk.Button(master=root, text='f(sin)', command=restore_from_pickle('figure_pickle', f))
#button = Tk.Button(master=root, text='Quit', command=_quit)
button.pack(side=Tk.BOTTOM)

Tk.mainloop()

The original code generates a GUI interface with a quit button:

https://www.dropbox.com/s/qqpprcfpiix5n45/original_code.png?dl=0

The code above just changes this button to display a different figure previously stored in a pickle file. However, when I run it, the initial plot does not display and the one in the pickle is not loaded either.

https://www.dropbox.com/s/lm889um1p13jr22/modified_code.png?dl=0

Any advice or any documentation which could help me would be most welcome.

[tacaswell]

This is probably better sent to matplotlib-users@python.org (https://mail.python.org/mailman/listinfo/matplotlib-users you will need to register to post un-moderated)

I do not think persisting figures as pickles is a good idea, it is better to persist your data and then have a function which creates the figure you need

def my_plotting_func(fig_or_ax, *args, **kwargs):
    # do some stuff
   ...

def create_from_file(fig_or_ax, fname):
    data_payload = from_disk(fname)
    return my_plotting_func(fig_or_ax, *data_payload['args'], **data_payload['kwargs'])

with data_payload being a dictionary that looks something like

data_payload = {'plot_name': 'my_plot',  # to do dispatch if you want
                'args': tuple(...),
                'kwargs': dict(..)}

Please follow up about this question on the user mailing list. It will be seen by a larger audience and we try to keep the issue tracker for feature requests / bug reports rather than usage questions.

Hope this helps!