The below code creates an animation of sine and cosine graph along with its intersection points. The animation works perfectly in jupyter notebook( I am using google colab). However, when I save animation in gif format , then it differs from the jupyter notebook animation. The intersection points are showing already in the saved animation(please second picture) ! Can anyone tell me why is it happening and how to fix the code. I think the code needs to be fixed at if statement which I wrote below.
(1) Animation playing inside notebook
(2) Saved Animation
and here is the code and my approach:
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation, PillowWriter
from matplotlib import rc
rc('animation', html='jshtml')
def truncation(values, decimals = 0):
"""
Truncate the value to the desired places.
"""
req_trunc = np.trunc(values*10**decimals)/10**decimals
return req_trunc
def animated_graph(x, y_1, y_2, label_list):
"""
Creates an animated graph
Arguments :
x -- values of x to draw the graphs
y_1, y_2 -- values of function f1 and f2 corresponding to x
Return :
ani : animation output
"""
# creates Figure and Axes objects
fig, ax = plt.subplots()
# set figure size
fig.set_size_inches(10,5)
# set x axis and y axis limit
ax.set_xlim(min(x)-1, max(x)+1)
ax.set_ylim(min(min(y_1), min(y_2))-1, max(max(y_1), max(y_2))+1)
# marker positions
pos_1, = ax.plot([], [], marker = "o", color = "red", ls = "", markersize = 10)
pos_2, = ax.plot([], [], marker = "o", color = "green", ls = "", markersize = 10)
# line graph
line_1, = ax.plot([], [], marker = "", color = "blue", ls ="-", lw = 2, label = label_list[0])
line_2, = ax.plot([], [], marker = "", color = "black", ls ="-", lw = 2, label = label_list[1] )
# coordinates annotation of marker
annotation_1 = ax.annotate('', xy=(0,0))
annotation_2 = ax.annotate('', xy=(0,0))
# add legend
plt.legend()
# animation function
def animate(i):
# update marker postions
pos_1.set_data(x[i], y_1[i])
pos_2.set_data(x[i], y_2[i])
# update line graph
line_1.set_data(x[:i], y_1[:i])
line_2.set_data(x[:i], y_2[:i])
# update lable
line_1.set_label(label_list[0])
line_2.set_label(label_list[1])
# update annotations i.e. coordinates
annotation_1.set_text(f"({x[i]}, {y_1[i]})")
annotation_1.set_position((x[i],y_1[i]))
annotation_2.set_text(f"({x[i]}, {y_2[i]})")
annotation_2.set_position((x[i],y_2[i]))
# Add coordinates for the intersection points.
if (x[i], y_1[i]) == (x[i], y_2[i]):
ax.text(x[i], y_1[i], f"{x[i],y_1[i]}", color = "m")
else :
pass
return pos_1, pos_2, line_1, line_2, annotation_1, annotation_2
ani = FuncAnimation(fig, animate, frames = len(x), interval = 150, repeat = True )
return ani
# x ranging from :
x_range = np.linspace(-2*np.pi, 2*np.pi, 129)
# sin(x)
sin_x = np.sin(x_range)
# cos(x)
cos_x = np.cos(x_range)
# truncation for intersection
x_range,sin_x, cos_x = truncation(x_range, 2), truncation(sin_x, 3), truncation(cos_x, 3)
# creating animation of sine cosine wave
sine_cos_animation = animated_graph(x_range, sin_x, cos_x, label_list = ["sin(x)", "cos(x)"])
sine_cos_animation
# animation saving
sine_cos_animation.save("sine_cos_animation.gif", writer = PillowWriter(fps = 20))