Animating a line plot over time

Question

Time series data is data over time. I am trying to animate a line plot of time series data in python. In my code below this translates to plotting xtraj as they and trange as the x. The plot does not seem to be working though.

I have found similar questions on Stack overflow but none of the solutions provided here seem to work. Some similar questions are matplotlib animated line plot stays empty, Matplotlib FuncAnimation not animating line plot and a tutorial referencing the help file Animations with Matplotlib.

I begin by creating the data with the first part and simulating it with the second. I tried renaming the data that would be used as y-values and x-values in order to make it easier to read.

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


dt = 0.01
tfinal = 5.0
x0 = 0


sqrtdt = np.sqrt(dt)
n = int(tfinal/dt)
xtraj = np.zeros(n+1, float)
trange = np.linspace(start=0,stop=tfinal ,num=n+1) 
xtraj[0] = x0

for i in range(n):
    xtraj[i+1] = xtraj[i] + np.random.normal() 

x = trange
y = xtraj

# animation line plot example

fig = plt.figure(4)
ax = plt.axes(xlim=(-5, 5), ylim=(0, 5))
line, = ax.plot([], [], lw=2)

def init():
    line.set_data([], [])
    return line,

def animate(i):
    line.set_data(x[:i], y[:i])
    return line,

anim = animation.FuncAnimation(fig, animate, init_func=init, frames=len(x)+1,interval=200, blit=False)
plt.show()

Any help would be highly appreciated. I am new to working in Python and particularly trying to animate plots. So I must apologize if this question is trivial.

Summary

So to summarize my question how does one animate time series in Python, iterating over the time steps (x-values).

Answer 1

Check this code:

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

dt = 0.01
tfinal = 1
x0 = 0

sqrtdt = np.sqrt(dt)
n = int(tfinal/dt)
xtraj = np.zeros(n+1, float)
trange = np.linspace(start=0,stop=tfinal ,num=n+1)
xtraj[0] = x0

for i in range(n):
    xtraj[i+1] = xtraj[i] + np.random.normal()

x = trange
y = xtraj

# animation line plot example

fig, ax = plt.subplots(1, 1, figsize = (6, 6))

def animate(i):
    ax.cla() # clear the previous image
    ax.plot(x[:i], y[:i]) # plot the line
    ax.set_xlim([x0, tfinal]) # fix the x axis
    ax.set_ylim([1.1*np.min(y), 1.1*np.max(y)]) # fix the y axis

anim = animation.FuncAnimation(fig, animate, frames = len(x) + 1, interval = 1, blit = False)
plt.show()

The code above reproduces this animation: