CODEWITHSUNDEEP
python-3.xmatplotlibmatplotlib-animation
An Ri
An Ri

Reputation: 476

How to update scatter with plot?

I am updating the graph, but can't join to it the scatter, could someone help me, please? I don't understand, how to realize it.

from matplotlib import pyplot as plt
from matplotlib.animation import FuncAnimation


fig = plt.figure()
ax = fig.add_subplot()
line = ax.plot([],[])[0]
x = []
y = []

scat = ax.scatter(x,y,c='Red')

def animate(i):
    x.append(i)
    y.append((-1)**i)
    line.set_data(x, y)
    ax.relim()
    ax.autoscale_view()

    return [line]

anim = FuncAnimation(fig, animate, frames=200, interval=100, blit=True)
plt.show()

I want to add dotes and their coordinates change only in X, Y should be 0.

enter image description here

Upvotes: 2

Views: 2276

Answers (1)

Mr. T
Mr. T

Reputation: 12410

Several problems have to be addressed here. You have to update the scatter plot, which is a PathCollection that is updated via .set_offsets(). This is in turn requires the x-y data to be in an array of the form (N, 2). We could combine the two lists x, y in every animation loop to such an array but this would be time-consuming. Instead, we declare the numpy array in advance and update it in the loop. As for axes labels, you might have noticed that they are not updated in your animation. The reason for this is that you use blitting, which suppresses redrawing all artists that are considered unchanged. So, if you don't want to take care manually of the axis limits, you have to turn off blitting.

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

fig, ax = plt.subplots()
line, = ax.plot([],[])
scat = ax.scatter([], [], c='Red')
n=200
#prepare array for data storage
pos = np.zeros((n, 2))

def animate(i):
    #calculate new x- and y-values
    pos[i, 0] = i
    pos[i, 1] = (-1)**i
    #update line data
    line.set_data(pos[:i, 0], pos[:i, 1])
    #update scatter plot data
    scat.set_offsets(pos[:i, :])
    #update axis view - works only if blit is False
    ax.relim()
    ax.autoscale_view()

    return scat, line

anim = FuncAnimation(fig, animate, frames=n, interval=100, blit=False)
plt.show()

Sample output: enter image description here

Upvotes: 2

Related Questions