Matplotlib multiple animate multiple lines - matplotlib

Question

I have been researching on how to animate multiple lines for a flight path. The object it that I read multiple GPS files time sync them them animate each path with respect to time. I found how to animate one line using append in the animate functions. Now I need to add a second and third for as many files are imported.
I know the problem is somewhere in how I perform the set_data with the lines. I ahve seen multiple example but I do not understand what structure is required to set up multiple lines. Yes I am a newbie.
fig = plt.figure()
ax1 = plt.axes(xlim=(-108, -104), ylim=(31,34))
line, = ax1.plot([], [], lw=2)
plt.xlabel('Longitude')
plt.ylabel('Latitude')
plotlays, plotcols = [2], ["black","red"]
lines = []
for index in range(2):
lobj = ax1.plot([],[],lw=2,color=plotcols[index])[0]
lines.append(lobj)
def init():
for line in lines:
line.set_data([],[])
return lines
x1,y1 = [],[]
x2,y2 = [],[]
frame_num = len(gps_data[0])
# animation function. This is called sequentially
def animate(i):
x = gps_data[0][i,3]
y = gps_data[0][i,2]
x1.append(x)
y1.append(y)
x = gps_data[1][i,3]
y = gps_data[1][i,2]
x2.append(x)
y2.append(y)
#X = np.array(x1, x2)
#Y = np.array(y1, y2)
#for index in range(0,1):
for lnum,line in enumerate(lines):
line.set_data([x1,y1, x2,y2])
return lines,
# call the animator. blit=True means only re-draw the parts that have changed.
anim = animation.FuncAnimation(fig, animate, init_func=init,
frames=frame_num, interval=1, blit=True)
plt.show()

Answer 1

The Matplotlib documentation for the line2d artist explains how set_data works. It "ACCEPTS: 2D array (rows are x, y) or two 1D arrays." It also works with lists. You've given it a four element list instead. You need to set the x and y data of each line separately. I've included an example with fake data below.
import matplotlib.pyplot as plt
from matplotlib import animation
from numpy import random
fig = plt.figure()
ax1 = plt.axes(xlim=(-108, -104), ylim=(31,34))
line, = ax1.plot([], [], lw=2)
plt.xlabel('Longitude')
plt.ylabel('Latitude')
plotlays, plotcols = [2], ["black","red"]
lines = []
for index in range(2):
lobj = ax1.plot([],[],lw=2,color=plotcols[index])[0]
lines.append(lobj)
def init():
for line in lines:
line.set_data([],[])
return lines
x1,y1 = [],[]
x2,y2 = [],[]
# fake data
frame_num = 100
gps_data = [-104 - (4 * random.rand(2, frame_num)), 31 + (3 * random.rand(2, frame_num))]
def animate(i):
x = gps_data[0][0, i]
y = gps_data[1][0, i]
x1.append(x)
y1.append(y)
x = gps_data[0][1,i]
y = gps_data[1][1,i]
x2.append(x)
y2.append(y)
xlist = [x1, x2]
ylist = [y1, y2]
#for index in range(0,1):
for lnum,line in enumerate(lines):
line.set_data(xlist[lnum], ylist[lnum]) # set data for each line separately.
return lines
# call the animator. blit=True means only re-draw the parts that have changed.
anim = animation.FuncAnimation(fig, animate, init_func=init,
frames=frame_num, interval=10, blit=True)
plt.show()

Answer 2

fig, ax1 = plt.subplots(figsize=(20,10))
plt.xticks()
ax1.set_xlabel("time")
ax1.set_ylabel("amp")
ax1.grid(True)
ox = get_data_o("/tmp/bf_ox.npy")
oy = get_data_o("/tmp/bf_oy.npy")
graphic_data = []
graphic_data.append(ax1.plot(ox, oy,"b-")[0])
sx = get_data_o("/tmp/bf_sx.npy")
i = 1
for p in sp.procs:
c = get_c(i)
sy = get_data_o("/tmp/bf_" + p + ".npy")
graphic_data.append(ax1.plot(sx, sy,c + "-")[0])
i = i + 1
def animate(i):
print ("frame")
ox = get_data_o("/tmp/bf_ox.npy")
oy = get_data_o("/tmp/bf_oy.npy")
i = 0
graphic_data[i].set_xdata(ox)
graphic_data[i].set_ydata(oy)
i = 1
sx = get_data_o("/tmp/bf_sx.npy")
for p in sp.procs:
sy = get_data_o("/tmp/bf_" + p + ".npy")
graphic_data[i].set_xdata(sx)
graphic_data[i].set_ydata(sy)
i = i + 1
return graphic_data
ani = animation.FuncAnimation(fig, animate, interval=2000, blit=True)
plt.show()