How to speed up tkinter embedded matplot lib and python

Question

I have a GUI that I am using to send a query data from an arduino. I then went to live graph this data without slow down. I currently am getting slow down with the more numbers

Answer 1

You need to use the matplotlib animation capabilities for the fastest response. Here's an example inside a tkinter window. I obviously can't test it since I don't have your arduino, so I commented out the arduino parts and added some random parts.

import Tkinter as tk
import serial
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from matplotlib.figure import Figure
from matplotlib import pyplot as plt
import matplotlib.animation as animation
from collections import deque
import random

HISTORY_LEN = 200

class App(tk.Frame):
    def __init__(self, master=None, **kwargs):
        tk.Frame.__init__(self, master, **kwargs)

        self.running = False
        self.ani = None

        btns = tk.Frame(self)
        btns.pack()

        lbl = tk.Label(btns, text="Number of points")
        lbl.pack(side=tk.LEFT)

        self.points_ent = tk.Entry(btns, width=5)
        self.points_ent.insert(0, '500')
        self.points_ent.pack(side=tk.LEFT)

        lbl = tk.Label(btns, text="update interval (ms)")
        lbl.pack(side=tk.LEFT)

        self.interval = tk.Entry(btns, width=5)
        self.interval.insert(0, '30')
        self.interval.pack(side=tk.LEFT)

        self.btn = tk.Button(btns, text='Start', command=self.on_click)
        self.btn.pack(side=tk.LEFT)

        self.fig = plt.Figure()
        self.ax1 = self.fig.add_subplot(111)
        self.line, = self.ax1.plot([], [], lw=2)
        self.canvas = FigureCanvasTkAgg(self.fig,master=master)
        self.canvas.show()
        self.canvas.get_tk_widget().pack()

    def on_click(self):
        if self.ani is None:
            return self.start()
        if self.running:
            self.ani.event_source.stop()
            self.btn.config(text='Un-Pause')
        else:
            self.ani.event_source.start()
            self.btn.config(text='Pause')
        self.running = not self.running

    def start(self):
        self.xdata = deque([], maxlen=HISTORY_LEN)
        self.ydata = deque([], maxlen=HISTORY_LEN)
        #~ self.arduinoData = serial.Serial('com5', 115200)
        #~ self.arduinoData.flushInput()
        self.points = int(self.points_ent.get()) + 1
        self.ani = animation.FuncAnimation(
            self.fig,
            self.update_graph,
            frames=self.points,
            interval=int(self.interval.get()),
            repeat=False)
        self.running = True
        self.btn.config(text='Pause')
        self.ani._start()

    def update_graph(self, i):
        self.xdata.append(i)
        #~ self.ydata.append(int(self.arduinoData.readline()))
        self.ydata.append(random.randrange(100)) # DEBUG
        self.line.set_data(self.xdata, self.ydata)
        self.ax1.set_ylim(min(self.ydata), max(self.ydata))
        self.ax1.set_xlim(min(self.xdata), max(self.xdata))
        if i >= self.points - 1:
            #~ self.arduinoData.close()
            self.btn.config(text='Start')
            self.running = False
            self.ani = None
        return self.line,

def main():
    root = tk.Tk()
    app = App(root)
    app.pack()
    root.mainloop()

if __name__ == '__main__':
    main()

For more speed, cut out the print functions. Printing to the terminal is very slow. Also, you may want to move the serial initialization to someplace where it's only called once.

For my computer, the fastest I could go was 25 ms / frame.