Alex Poca Alex Poca - 3 months ago 18
Python Question

Matplotlib animation: how to make some lines not visible

I am reading some sensors values by serial port.

I would like to be able to show/hide the respective lines according to key presses.

Here is the code: it has been overly simplified (sorry it is long anyway).
I would like to make ALL blue lines in the 3 subplots show/hide by pressing 1; all red lines show/hide by pressing 2.

I can only "freeze" the lines but not hide them.

What am I missing?

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

# arrays of last 100 data (range 0.-1.)
# read from serial port in a dedicated thread
val1 = np.zeros(100)
val2 = np.zeros(100)

speed1=[] # speed of change of val1 and val2
speed2=[]

accel1=[] # speed of change of speed1 and speed2
accel2=[]

# initial level for each channel
level1 = 0.2
level2 = 0.8

fig, ax = plt.subplots()

ax = plt.subplot2grid((3,1),(0,0))
lineVal1, = ax.plot(np.zeros(100))
lineVal2, = ax.plot(np.zeros(100), color = "r")
ax.set_ylim(-0.5, 1.5)

axSpeed = plt.subplot2grid((3,1),(1,0))
lineSpeed1, = axSpeed.plot(np.zeros(99))
lineSpeed2, = axSpeed.plot(np.zeros(99), color = "r")
axSpeed.set_ylim(-.1, +.1)

axAccel = plt.subplot2grid((3,1),(2,0))
lineAccel1, = axAccel.plot(np.zeros(98))
lineAccel2, = axAccel.plot(np.zeros(98), color = "r")
axAccel.set_ylim(-.1, +.1)


showLines1 = True
showLines2 = True

def onKeyPress(event):
global showLines1, showLines2
if event.key == "1": showLines1 ^= True
if event.key == "2": showLines2 ^= True



def updateData():
global level1, level2
global val1, val2
global speed1, speed2
global accel1, accel2

clamp = lambda n, minn, maxn: max(min(maxn, n), minn)

# level1 and level2 are really read from serial port in a separate thread
# here we simulate them
level1 = clamp(level1 + (np.random.random()-.5)/20.0, 0.0, 1.0)
level2 = clamp(level2 + (np.random.random()-.5)/20.0, 0.0, 1.0)


# last reads are appended to data arrays
val1 = np.append(val1, level1)[-100:]
val2 = np.append(val2, level2)[-100:]

# as an example we calculate speed and acceleration on received data
speed1=val1[1:]-val1[:-1]
speed2=val2[1:]-val2[:-1]

accel1=speed1[1:]-speed1[:-1]
accel2=speed2[1:]-speed2[:-1]

yield 1 # FuncAnimation expects an iterator



def visualize(i):

if showLines1:
lineVal1.set_ydata(val1)
lineSpeed1.set_ydata(speed1)
lineAccel1.set_ydata(accel1)

if showLines2:
lineVal2.set_ydata(val2)
lineSpeed2.set_ydata(speed2)
lineAccel2.set_ydata(accel2)

return lineVal1,lineVal2, lineSpeed1, lineSpeed2, lineAccel1, lineAccel2

fig.canvas.mpl_connect('key_press_event', onKeyPress)

ani = animation.FuncAnimation(fig, visualize, updateData, interval=50)
plt.show()

Answer

You should hide/show the lines:

lineVal1.set_visible(showLines1)
lineSpeed1.set_visible(showLines1)
lineAccel1.set_visible(showLines1)

lineVal2.set_visible(showLines2)
lineSpeed2.set_visible(showLines2)
lineAccel2.set_visible(showLines2)
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