how to use blit=true for animation subplot in python tkinter - python-3.x

Question

The following code is a simplified version of my project, and it could run and plot with animation, but I have to add blit=true in the animation to speed up (my original UI is much more complicated and slow). I know the animation function must return a sequence of Artist objects. here what is the artist object in my subplot_2? I tried subplot_2,a,f, none of them work. Many thanks
from multiprocessing import Process
import matplotlib
matplotlib.use("TkAgg")
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
##, NavigationToolbar2TkAgg
from matplotlib.figure import Figure
import matplotlib.animation as animation
from matplotlib import style
import tkinter as tk
from tkinter import ttk
from tkinter import *
import matplotlib.pyplot as plt
import numpy as np
f = Figure(figsize=(6,6), dpi=100)
subplot_1 = f.add_subplot(211)
subplot_2 = f.add_subplot(212)
LARGE_FONT= ("Verdana", 12)
style.use("ggplot")
def animate(i):
time = np.random.rand(2, 25)
data = np.random.rand(2, 25)
a = subplot_2.scatter(time,data,c='blue',s=2)
#return a
class home(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
tk.Tk.wm_title(self, "Graph ")
self.geometry("1000x1000")
container = tk.Frame(self)
container.pack(side="top", fill="both", expand = True)
container.grid_rowconfigure(0, weight=1)
container.grid_columnconfigure(0, weight=1)
self.frames = {}
F=Graph
frame=Graph(container, self)
self.frames[F] = frame
frame.grid(row=0, column=0, sticky="nsew")
self.show_frame(Graph)
def show_frame(self, cont):
frame = self.frames[cont]
frame.tkraise()
def get_frame(self, frame_class):
return self.frames[frame_class]
##
class Graph(tk.Frame):
def __init__(self, parent, controller):
global canvas
tk.Frame.__init__(self, parent)
label = tk.Label(self, text=" ", font=LARGE_FONT)
label.pack(pady=120,padx=10)
collectbtn=Button(self,text='collect',command=self.clickstart)
collectbtn.place(x=200,y=100)
canvas = FigureCanvasTkAgg(f, self)
## canvas.draw()
canvas.get_tk_widget().pack(side=tk.BOTTOM, fill=tk.BOTH, expand=True)
canvas._tkcanvas.pack(side=tk.TOP, fill=tk.BOTH, expand=True)
def clickstart(self):
animate(0)
#aniplot_photon = animation.FuncAnimation(f, animate, blit=True,interval=100)
aniplot_photon = animation.FuncAnimation(f, animate, interval=100)
canvas.draw()
app = home()
app.mainloop()
Updates:
Thanks to the William's answer, it works. However, I have further questions, if this subplot include many curves "subplot_2.scatter(x1..),subplot_2.scatter(x2..),subplot_2.scatter(x3..),subplot_2.scatter(x1..)...", or some subplots are updated from different threads (make objects and global them?), it will be hard to put all curves into return list. However, I found a simple solution for the above listed problems, I could just use return [subplot_2] and it will update all plots inside subplot_2, but the coordinates(x ticks) are lost (run and you will see). is there a simple way I could keep the coordinates when I use return [suplot_2]?
def animate(i):
time = np.random.rand(2, 25)
data = np.random.rand(2, 25)
a = subplot_2.scatter(time,data,c='blue',s=2)
return [subplot_2]

Answer 1

matplotlib.pyplot.scatter returns an artist (a PathCollection to be exact), so the artist you need to return from animate is stored in a. However, FuncAnimation requires a sequence of artists, so
return a
is insufficient (as this is a single artist, not a sequence). You can use one of
return [a]
or
return a,
to satisfy the "sequence of artists" requirement.