How to pass arguments to animation.FuncAnimation()?

Question

How to pass arguments to animation.FuncAnimation()? I tried, but didn't work. The signature of animation.FuncAnimation() is

class matplotlib.animation.FuncAnimation(fig, func, frames=None, init_func=None, fargs=None, save_count=None, **kwargs) Bases: matplotlib.animation.TimedAnimation

I have pasted my code below. Which changes I have to make?

import matplotlib.pyplot as plt
import matplotlib.animation as animation

def animate(i,argu):
    print argu

    graph_data = open('example.txt','r').read()
    lines = graph_data.split('\n')
    xs = []
    ys = []
    for line in lines:
        if len(line) > 1:
            x, y = line.split(',')
            xs.append(x)
            ys.append(y)
        ax1.clear()
        ax1.plot(xs, ys)
        plt.grid()

ani = animation.FuncAnimation(fig,animate,fargs = 5,interval = 100)
plt.show()

Answer 1

Check this simple example:

# -*- coding: utf-8 -*-
import matplotlib.pyplot as plt 
import matplotlib.animation as animation
import numpy as np

data = np.loadtxt("example.txt", delimiter=",")
x = data[:,0]
y = data[:,1]

fig = plt.figure()
ax = fig.add_subplot(111)
line, = ax.plot([],[], '-')
line2, = ax.plot([],[],'--')
ax.set_xlim(np.min(x), np.max(x))
ax.set_ylim(np.min(y), np.max(y))

def animate(i,factor):
    line.set_xdata(x[:i])
    line.set_ydata(y[:i])
    line2.set_xdata(x[:i])
    line2.set_ydata(factor*y[:i])
    return line,line2

K = 0.75 # any factor 
ani = animation.FuncAnimation(fig, animate, frames=len(x), fargs=(K,),
                              interval=100, blit=True)
plt.show()

First, for data handling is recommended to use NumPy, is simplest read and write data.

Isn't necessary that you use the "plot" function in each animation step, instead use the set_xdata and set_ydata methods for update data.

Also reviews examples of the Matplotlib documentation: http://matplotlib.org/1.4.1/examples/animation/.