Matplotlib figure.savefig() tkinter

Question

I have embedded my matplotlib plot in tkinter according to http://matplotlib.org/examples/user_interfaces/embedding_in_tk2.html successfully, but I also want to save my plot. How do I do this? I tried figure.savefig (as below); I thought this would work from looking at http://matplotlib.org/api/figure_api.html :

#!/usr/bin/env python
import matplotlib
matplotlib.use('TkAgg')

from numpy import arange, sin, pi
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg
from matplotlib.figure import Figure

import sys
if sys.version_info[0] < 3:
    import Tkinter as Tk
else:
    import tkinter as Tk

def destroy(e): sys.exit()

root = Tk.Tk()
root.wm_title("Embedding in TK")
#root.bind("<Destroy>", destroy)


f = Figure(figsize=(5,4), dpi=100)
a = f.add_subplot(111)
t = arange(0.0,3.0,0.01)
s = sin(2*pi*t)

a.plot(t,s)
a.set_title('Tk embedding')
a.set_xlabel('X axis label')
a.set_ylabel('Y label')

f.savefig('hello.png')

# 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)

button = Tk.Button(master=root, text='Quit', command=sys.exit)
button.pack(side=Tk.BOTTOM)

Tk.mainloop()

Answer 1

The Figure needs a FigureCanvas to draw on. In other words, don't call savefig until after the FigureCanvas has been established:

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