How do I change the interval between frames (python)?

Question

So I'm making an animation in python using matplotlib.animation, and I want the time between each frame to change on every frame. According to everything I've found so far, the 'interval' arg can only be an int where I want it to be an array. Code so far:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.lines import Line2D
import matplotlib.animation as animation
import time

data=np.loadtxt("coord_dump.dat")
r=(data[:,0]**2+data[:,2]**2)**0.5
distance=np.diff(r)
ti=np.abs(distance)*1e-9
tt=0

fig = plt.figure()
ax=plt.axes(xlim=(-2e16,2e16),ylim=(-1.5e16,1.5e16))
ax.set_xlabel('x(cm)')
ax.set_ylabel('y(cm)')

x1 = data[:,0]
y1 = data[:,2]
x2 = data[:,1]
y2 = data[:,3]
line1 = Line2D([], [], color='black')
line1a = Line2D([], [], color='black', marker='o', markersize=6)
line2= Line2D([], [], color='red')
line2a = Line2D([], [], color='red', marker='o', markersize=6)
ax.add_line(line1)
ax.add_line(line2)
ax.add_line(line1a)
ax.add_line(line2a)

def animate(i):

    line1.set_data(x1[:i], y1[:i])
    line1a.set_data(x1[i], y1[i])
    line2.set_data(x2[:i], y2[:i])
    line2a.set_data(x2[i], y2[i])
    lines =  [line1, line1a, line2, line2a]
    tt=ti[i]
    return lines,tt

def init():
    lines =  [line1, line1a, line2, line2a]
    for l in lines:
        l.set_data([], [])
    return lines,

ani = animation.FuncAnimation(fig,animate,frames=15000, interval=5+tt,init_func=init, blit=True)
print tt
ani.save('xy2.mp4')
plt.show()

Basically I want interval=ti[i] for frame i. (yes I know my code is inefficient, I'm new to python and I just hobbled this together from a bunch of websites) Also if this is impossible, is there a simple way to edit the movie afterwards to achieve the same effect?

Jinguo Liu · Accepted Answer · 2017-05-16 04:18:05Z

1

You can change ani.event_source.interval, like the following code

def animate(i):

    line1.set_data(x1[:i], y1[:i])
    line1a.set_data(x1[i], y1[i])
    line2.set_data(x2[:i], y2[:i])
    line2a.set_data(x2[i], y2[i])
    lines =  [line1, line1a, line2, line2a]
    tt=ti[i]
    ani.event_source.interval = tt
    return lines,

Warning: it seems not compatible with GIF file.

answered May 16, 2017 at 4:18

Jinguo Liu

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