[pyqtgraph] Slow updating plots with 3 curves

[Marco Massaro]

Hello,

I need to build an updating plot using 3 curves. I have tried with this
following code but the resultant plot is drastically slower than one single
plot:


#!/usr/bin/python


from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg

import time
import numpy as np


app = QtGui.QApplication([])



win = pg.GraphicsWindow()

p1 = win.addPlot()
p2 = win.addPlot()
p3 = win.addPlot()


curve1 = p1.plot()

curve2 = p2.plot()

curve3 = p3.plot()

readData = [0.0, 0.0, 0.0]
y1=[0.0]
y2=[0.0]
y3=[0.0]

temp = [0.0]

start = time.time()

def update():
global curve1, curve2, curve3
t = time.time()-start # measure of time as x-coordinate
readData= readfun() #it returns a list of 3 elements that have
to be the y-coordinates for the updating plots
y1.append(readData[0])
y2.append(readData[1])
y3.append(readData[2])
temp.append(t)

curve1.setData(temp,y1)
curve2.setData(temp,y2)
curve3.setData(temp,y3)
app.processEvents()



timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(0)




if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_'):
QtGui.QApplication.instance().exec_()

[Pete Bachant]

It looks like you're creating 3 plots. Can you create one and add three
curves to it, i.e.,

plot = pg.addPlot()
curve1 = plot.plot()
curve2 = plot.plot()
curve3 = plot.plot()

Post by Marco Massaro
Hello,
I need to build an updating plot using 3 curves. I have tried with this
following code but the resultant plot is drastically slower than one single
#!/usr/bin/python
from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg
import time
import numpy as np
app = QtGui.QApplication([])
win = pg.GraphicsWindow()
p1 = win.addPlot()
p2 = win.addPlot()
p3 = win.addPlot()
curve1 = p1.plot()
curve2 = p2.plot()
curve3 = p3.plot()
readData = [0.0, 0.0, 0.0]
y1=[0.0]
y2=[0.0]
y3=[0.0]
temp = [0.0]
start = time.time()
global curve1, curve2, curve3
t = time.time()-start # measure of time as x-coordinate
readData= readfun() #it returns a list of 3 elements that have
to be the y-coordinates for the updating plots
y1.append(readData[0])
y2.append(readData[1])
y3.append(readData[2])
temp.append(t)
curve1.setData(temp,y1)
curve2.setData(temp,y2)
curve3.setData(temp,y3)
app.processEvents()
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(0)
import sys
QtGui.QApplication.instance().exec_()

[Pete Bachant]

It looks like you're creating 3 plots. Can you create one and add three
curves to it?

plot = win.addPlot()
curve1 = plot.plot()
curve2 = plot.plot()
curve3 = plot.plot()