Hello. I'm trying to plot random walk values with an arrow that points the
lastest value.
Here I attach my code that I made with the help of one of the module's
great examples! I tested this under Python 3.6(32bit)
*randomWalk function* returns random walk values and *update2 function*
puts them into a deque named *data3. *
It works well and I can see an arrow that follows the newest value plotting
on the graph, but whenever I run the program, I see an error that sys:
Traceback (most recent call last):
File
"d:\python36-32\lib\site-packages\pyqtgraph\graphicsItems\CurvePoint.py",
line 64, in event
index = (len(x)-1) * np.clip(pos, 0.0, 1.0)
TypeError: object of type 'NoneType' has no len()
Traceback (most recent call last):
File
"d:\python36-32\lib\site-packages\pyqtgraph\graphicsItems\CurvePoint.py",
line 74, in event
i1 = np.clip(index-1, 0, len(x)-1)
TypeError: object of type 'NoneType' has no len()
I guess that the error might stem from the code curvePoint.setPos(
len(data3) ), but I couldn't find out how to fix it.
I referred to the manual and Text Item, Arrow examples, but the arrows in
the examples trace static formulas and I'm having trouble applying it to my
real-time program.
I'd appreciate it if I could get some help on solving this problem.
Thank you for reading this.
from collections import deque
import pyqtgraph as pg
import numpy as np
t = 0
walk = 0
pg.setConfigOption('background', 'w')
pg.setConfigOption('foreground', 'k')
win = pg.GraphicsWindow()
win.setWindowTitle('pyqtgraph example: Scrolling Plots')
win.nextRow()
p3 = win.addPlot()
p3.setDownsampling(mode='peak')
p3.setClipToView(True)
p3.setRange(xRange=[-10000, 0])
p3.setLimits(xMax=0)
curve3 = p3.plot(pen=None, symbol='o', symbolPen=None, symbolSize=2,
symbolBrush=(102, 000, 000, 255))
curvePoint = pg.CurvePoint(curve3)
arrow2 = pg.ArrowItem(angle=310)
arrow2.setParentItem(curvePoint)
data3 = deque()
def randomWalk():
global t, walk
t = np.random.randint(-1,2)
walk += t
return walk
def update2():
global data3, curvePoint
data3.append( randomWalk() )
if len(data3) <= 10000:
curve3.setData(data3)
curve3.setPos(-10000, 0)
curvePoint.setPos( len(data3) )
else:
data3.popleft()
curve3.setData(data3)
curve3.setPos(-10000, 0)
curvePoint.setPos( len(data3) )
def update():
update2()
timer = pg.QtCore.QTimer()
timer.timeout.connect(update)
timer.start(1)
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