Adding labels to 3D plotlines in matplotlib.animation

Question

I'm trying to add labels to animated 3D plotlines using matplotlib.animation. The sample code I am using is based on this example from the matplotlib example files EDIT: full code is here:

import numpy as np
import matplotlib.pyplot as plt
import mpl_toolkits.mplot3d.axes3d as p3
import matplotlib.animation as animation

# Fixing random state for reproducibility
np.random.seed(19680801)


def Gen_RandLine(length, dims=2):
"""
Create a line using a random walk algorithm

length is the number of points for the line.
dims is the number of dimensions the line has.
"""
lineData = np.empty((dims, length))
lineData[:, 0] = np.random.rand(dims)
for index in range(1, length):
    # scaling the random numbers by 0.1 so
    # movement is small compared to position.
    # subtraction by 0.5 is to change the range to [-0.5, 0.5]
    # to allow a line to move backwards.
    step = ((np.random.rand(dims) - 0.5) * 0.1)
    lineData[:, index] = lineData[:, index - 1] + step

return lineData


def update_lines(num, dataLines, lines):
    for line, data in zip(lines, dataLines):
    # NOTE: there is no .set_data() for 3 dim data...
        line.set_data(data[0:2, :num])
        line.set_3d_properties(data[2, :num])
    return lines

# Attaching 3D axis to the figure
fig = plt.figure()
ax = p3.Axes3D(fig)

# Four lines of random 3-D lines
data = [Gen_RandLine(25, 3) for index in range(4)]

# Creating fifty line objects.
# NOTE: Can't pass empty arrays into 3d version of plot()
lines = [ax.plot(dat[0, 0:1], dat[1, 0:1], dat[2, 0:1])[0] for 
dat in data]

# Setting the axes properties
ax.set_xlim3d([0.0, 1.0])
ax.set_xlabel('X')

ax.set_ylim3d([0.0, 1.0])
ax.set_ylabel('Y')

ax.set_zlim3d([0.0, 1.0])
ax.set_zlabel('Z')

ax.set_title('3D Test')

# Creating the Animation object
line_ani = animation.FuncAnimation(fig, update_lines, 25, fargs= 
   (data, lines),
                               interval=50, blit=False)

plt.show()

''''

What this does is plots a series of lines in 3D using randomly generated points.

I've reduced the number of plotted animated lines to 4 and I'd like to like to put a label (A,B,C,D) onto the origin point of the lines. I have looked in the API but can only see how to label the axes and ticks, not the plotted data.

Answer 1

I think we can add a string to the initial graph with the annotation function and make the animation work. So after setting up the graph, I add the text using the initial data for the animation.

# Attaching 3D axis to the figure
fig = plt.figure()
ax = p3.Axes3D(fig)

# Four lines of random 3-D lines
data = [Gen_RandLine(25, 3) for index in range(4)]

# add text
name = ['A','B','C','D']
colors = ['blue','orange','green','red']
for i,d in enumerate(data):
    #print('idx:'+str(i), d[0][0], d[1][0], d[2][0])
    ax.text(d[0][0],d[1][0],d[2][0], s=name[i], size=18, color=colors[i])
            
# Creating fifty line objects.
# NOTE: Can't pass empty arrays into 3d version of plot()
lines = [ax.plot(dat[0, 0:1], dat[1, 0:1], dat[2, 0:1])[0] for dat in data]

# Setting the axes properties
ax.set_xlim3d([0.0, 1.0])
ax.set_xlabel('X')

ax.set_ylim3d([0.0, 1.0])
ax.set_ylabel('Y')

ax.set_zlim3d([0.0, 1.0])
ax.set_zlabel('Z')

ax.set_title('3D Test')

# Creating the Animation object
line_ani = animation.FuncAnimation(fig, update_lines, 25, fargs=(data, lines), interval=50, blit=False)

plt.show()