[PYTHON] Flexible animation creation using animation.FuncAnimation of matplotlib

For matplotlib in python,

• animation.FuncAnimation

There is a function that can flexibly create animation. How to use this function.

** Sample program **

sample_animation.py

import matplotlib.animation as anm
import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure(figsize = (10, 6))
x = np.arange(0, 10, 0.1)

def update(i, fig_title, A):
	if i != 0:
		plt.cla()                      #Erase the currently depicted graph

	y = A * np.sin(x - i)
	plt.plot(x, y, "r")
	plt.title(fig_title + 'i=' + str(i))


ani = anm.FuncAnimation(fig, update, fargs = ('Initial Animation! ', 2.0), \
	interval = 100, frames = 132)

ani.save("Sample.gif", writer = 'imagemagick')

If you execute the above code, the following animation file "Sample.gif" should be generated.

** Explanation of sample program **

The key is

ani = anm.FuncAnimation(fig, update, fargs = ('Initial Animation! ', 2.0), \
	interval = 100, frames = 132)

A sentence.

1st argument fig

figure object. Give commands related to figures (animation) to this object.

2nd argument update

A callback function that creates each of the figures that make up the animation. Creating an animation means creating multiple diagrams and stitching them together, but with the `` `FuncAnimationfunction, you can call it multiple times by calling the function that creates the diagram. It has been realized.update```The rules of the function are as follows.

--Define before the FuncAnimation function. --Make sure that the figure is initialized when this function is called the second time or later. --The `plt.cla ()` part of the above sample program corresponds to it. --This function has at least one argument. --The first argument of this function (i in the above sample program) is an integer that increments from 0 to 1 each time this function is called. --If you want to have two or more arguments to this function, specify it with `` `fargs``` (described later).

Option fargs

An option that allows you to specify the second and subsequent arguments when you want to provide two or more arguments to the update function of the second argument. In the example of the above sample program, `" Initial Animation! "``` Is in the second argument fig_title``` of the ```update``` function, and the third argument ```A. 2.0 is passed to `` respectively.

Optional interval

You can specify the time interval at which the figure changes in the animation (in milliseconds). interval = 100Then, "the figure changes once every 100 milliseconds".

Optional frames

Specify the number of times to call the update function. frames = 132ThenupdateThe function is called 132 times, and the generated gif animation is a combination of 132 still images. (The first argument of the update function, i, takes the value 0,1, ..., 131 in the meantime)

Reference URL

• http://matplotlib.org/api/animation_api.html
• http://cflat-inc.hatenablog.com/entry/2014/03/17/214719
• http://qiita.com/Tatejimaru137/items/3fdcc38cf8247b7056aa
• http://qiita.com/yubais/items/c95ba9ff1b23dd33fde2