Matplotlib create real time animated graph

Question

I am having a hard time setting up my code to create a real time animated graph, my code is graphing after the data is being collected, not showing every iteration. My scrip

Answer 1

Solution for pre-computed results

This makes a decent animation from the data in your output file:

from matplotlib import pyplot as plt
from matplotlib import animation


fig = plt.figure()

with open('error_output.txt') as fobj:
    x, y = zip(*([float(x) for x in line.split(',')] for line in fobj))


def animate(n):
    line, = plt.plot(x[:n], y[:n], color='g')
    return line,

anim = animation.FuncAnimation(fig, animate, frames=len(x), interval=1000)
plt.show()

Solution for a real-time animation as the values are computed

Here a version that allows real-time animation of data produce by regr_magic:

import random
import time

from matplotlib import pyplot as plt
from matplotlib import animation


class RegrMagic(object):
    """Mock for function Regr_magic()
    """
    def __init__(self):
        self.x = 0
    def __call__(self):
        time.sleep(random.random())
        self.x += 1
        return self.x, random.random()

regr_magic = RegrMagic()

def frames():
    while True:
        yield regr_magic()

fig = plt.figure()

x = []
y = []
def animate(args):
    x.append(args[0])
    y.append(args[1])
    return plt.plot(x, y, color='g')


anim = animation.FuncAnimation(fig, animate, frames=frames, interval=1000)
plt.show()

The class RegrMagic is a helper the mocks Regr_magic(). The __call__method makes an instance of this class behave like a function. It has state and produces the numbers 1, 0.56565, 2, 0.65566 etc. for each call (second number is a random number). It also has a time delay to mimic the computation time.

The important thing is frames(). Replace Regr_magic() with Regr_magic() and should be good to go.

Solution for the concrete problem

A version without mocks:

import random
import time

from matplotlib import pyplot as plt
from matplotlib import animation


def frames():
    while True:
        yield Regr_magic()


fig = plt.figure()

x = []
y = []
def animate(args):
    x.append(args[0])
    y.append(args[1])
    return plt.plot(x, y, color='g')


anim = animation.FuncAnimation(fig, animate, frames=frames, interval=1000)
plt.show()