How to animate an array selection with matplotlib animation?

Question

I'm learning to work with the matplotlib animation function. I took the tutorial from matplotlib and changed a bit. So far I'm able to show my complete array (list) with length of 10. (see code)

My goal is to see in every frame only e.g. 3 values from the array at the same time. In the next frame the "window" should slide over with the stepsize of 1 Index so that the "old" values will move to the left and at the right are the "more new" values:

1st frame - see values list[3],list[2],list[1] from the array

2nd frame - see values list[4],list[3],list[2] from the array

3rd frame - see values list[5],list[4],list[3] from the array

....

Base Code from matplotlib tutorial, just a bit modified to show my complete array (list) but without updating.

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

fig, ax = plt.subplots()
list = np.array([1,8,3,4,5,3,2,1,5,1])
line, = ax.plot(np.random.rand(10))
ax.set_ylim(0, 10)


def update(data):
    line.set_ydata(data)
    return line,

def data_gen():
    while True:
        #yield np.random.rand(4)
        yield list

ani = animation.FuncAnimation(fig, update, data_gen, interval=500)
plt.show()

I dont know how I can "slide" my window and then to update the animation. Probably with a for loop over the index of the frames I guess... ?

Which variable consists the index of the frames?

Thx a lot for your time. Have a nice weekend !

Diziet Asahi · Accepted Answer · 2018-10-27 12:11:29Z

4

I don't know what you were trying to do with your generator, but I think this is what you are trying to do?

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

point_to_show = 3
my_list = np.array([1,8,3,4,5,3,2,1,5,1])

fig, ax = plt.subplots()
line, = ax.plot(range(point_to_show),np.zeros(point_to_show)*np.NaN, 'ro-')
ax.set_ylim(0, 10)
ax.set_xlim(0, point_to_show-1)

def update(i):
    new_data = my_list[i:i+point_to_show]
    line.set_ydata(new_data)
    return line,

ani = animation.FuncAnimation(fig, update, frames=len(my_list)-point_to_show, interval=500)
plt.show()

answered Oct 27, 2018 at 12:11

Diziet Asahi

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1 Comment

HKC72 Over a year ago

That's the solution I was looking for. Now I understood how to work with the animation and the indicies. Thanks a lot Diziet ! I just want to display the values of a proces. I tried to keep my example / question as easy as possible. Have a good day !

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