You need to initially set some data when defining the curve:
Cheers,
Vasilije
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))
# new:
curve3.setData([0],[0])
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)
# new:
from pyqtgraph import QtGui
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
On Wed, Jul 12, 2017 at 4:52 AM, <[email protected]> wrote:
> 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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