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Getting a recursion error when connecting a pyqtgraph linearregionitem with a plotitem's axis

I'm trying to do something similar to what is done in the pyqtgraph example 'Crosshair/Mouse Interaction'. Basically I want to connect a linear region item on one plot, to the x-axis on another plot. then one plot will show the data that's in the linearregionitem, and you can zoom in and out by changing the linearregionitem, and vice-versa.
My problem is that it crashes with:
RecursionError: maximum recursion depth exceeded while calling a
Python object
Here is the code from the example if you want to try it to give you an idea of what I want to do...
"""
Demonstrates some customized mouse interaction by drawing a crosshair that follows
the mouse.
"""
import numpy as np
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore
from pyqtgraph.Point import Point
#generate layout
app = QtGui.QApplication([])
win = pg.GraphicsWindow()
win.setWindowTitle('pyqtgraph example: crosshair')
label = pg.LabelItem(justify='right')
win.addItem(label)
p1 = win.addPlot(row=1, col=0)
p2 = win.addPlot(row=2, col=0)
region = pg.LinearRegionItem()
region.setZValue(10)
# Add the LinearRegionItem to the ViewBox, but tell the ViewBox to exclude this
# item when doing auto-range calculations.
p2.addItem(region, ignoreBounds=True)
#pg.dbg()
p1.setAutoVisible(y=True)
#create numpy arrays
#make the numbers large to show that the xrange shows data from 10000 to all the way 0
data1 = 10000 + 15000 * pg.gaussianFilter(np.random.random(size=10000), 10) + 3000 * np.random.random(size=10000)
data2 = 15000 + 15000 * pg.gaussianFilter(np.random.random(size=10000), 10) + 3000 * np.random.random(size=10000)
p1.plot(data1, pen="r")
p1.plot(data2, pen="g")
p2.plot(data1, pen="w")
def update():
region.setZValue(10)
minX, maxX = region.getRegion()
p1.setXRange(minX, maxX, padding=0)
region.sigRegionChanged.connect(update)
def updateRegion(window, viewRange):
rgn = viewRange[0]
region.setRegion(rgn)
p1.sigRangeChanged.connect(updateRegion)
region.setRegion([1000, 2000])
#cross hair
vLine = pg.InfiniteLine(angle=90, movable=False)
hLine = pg.InfiniteLine(angle=0, movable=False)
p1.addItem(vLine, ignoreBounds=True)
p1.addItem(hLine, ignoreBounds=True)
vb = p1.vb
def mouseMoved(evt):
pos = evt[0] ## using signal proxy turns original arguments into a tuple
if p1.sceneBoundingRect().contains(pos):
mousePoint = vb.mapSceneToView(pos)
index = int(mousePoint.x())
if index > 0 and index < len(data1):
label.setText("<span style='font-size: 12pt'>x=%0.1f, <span style='color: red'>y1=%0.1f</span>, <span style='color: green'>y2=%0.1f</span>" % (mousePoint.x(), data1[index], data2[index]))
vLine.setPos(mousePoint.x())
hLine.setPos(mousePoint.y())
proxy = pg.SignalProxy(p1.scene().sigMouseMoved, rateLimit=60, slot=mouseMoved)
#p1.scene().sigMouseMoved.connect(mouseMoved)
## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
If you don't want to read all that, the linearregionitem and the plotitem are connected via the lines...
def update():
region.setZValue(10)
minX, maxX = region.getRegion()
p1.setXRange(minX, maxX, padding=0)
region.sigRegionChanged.connect(update)
def updateRegion(window, viewRange):
rgn = viewRange[0]
region.setRegion(rgn)
p1.sigRangeChanged.connect(updateRegion)
Here's a minimal working example of my code...I'm doing pretty much the same thing, but I'm doing it in a class...
When you run it, it will crash if you adjust the linearregionitem, or if you change the axis of plotA. If you comment out either of the 'connect' lines, then the program will work (half-way).
import pyqtgraph as pg
import sys
# PyQt5 includes
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication
class MyApplicationWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.__buildUI()
def __buildUI(self):
plotWidget = pg.GraphicsLayoutWidget()
self.PlotA = pg.PlotItem()
self.PlotA.setXRange(10, 20)
self.PlotB = pg.PlotItem()
self.PlotB.setXRange(0, 100)
self.lri = pg.LinearRegionItem()
self.lri.setRegion((10, 20))
self.PlotB.addItem(self.lri)
# The following two connections set up a recursive loop
self.lri.sigRegionChanged.connect(self.update)
self.PlotA.sigRangeChanged.connect(self.update_lri)
plotWidget.addItem(self.PlotA)
plotWidget.nextRow()
plotWidget.addItem(self.PlotB)
self.setCentralWidget(plotWidget)
self.show()
def update(self):
minX, maxX = self.lri.getRegion()
self.PlotA.setXRange(minX, maxX)
def update_lri(self, window, viewRange):
A_xrange = viewRange[0]
self.lri.setRegion(A_xrange)
if __name__ == '__main__':
app = QApplication(sys.argv)
widget = MyApplicationWindow()
sys.exit(app.exec_())
What's happening? Can anyone tell me how to get this working? This is in Python 3.6

+1 for proving a good MVCE. This allowed me to experiment a bit and I found the issue. Couldn't have solved it without it.
You must set the padding to zero when updating the x range of the plot. So change the update method to:
def update(self):
minX, maxX = self.lri.getRegion()
self.PlotA.setXRange(minX, maxX, padding=0)
Typically with QT these infinite signal loops are prevented by only updating a variable (and emitting the corresponding signal) when the new value is different from the old value. Somewhere in Qt/PyQtGraph this check is also done. But since your padding isn't zero, the new xrange will be a little bigger than the old xrange every iteration, and the loop doesn't end.
BTW, it is common in Python to let variable names start with a lower case character, and class names with upper case. I recommend to rename self.PlotA to self.plotA. This makes your code better readable for other Python programmers. Also it will give better syntax highlighting here on Stack Overflow.

pyqtgraph - move origin of ArrowItem to local center

I'm using pyqtgraph to plot tracks of a robot (the path that the bot drove). Now I want to add a marker to the plot to indicate the bots current position and heading. I thought ArrowItem would be the right choice, because it is scale invariant and can be rotated easily. However the local origin of the arrow is at its tip like this
but I want it to be in the center like this
How can I do that? I would also appreciate different solutions to this problem.
Update
After applying eyllansec's code I get some rendering problems. A minimal example (one has to zoom or move the view to disable the auto scaling):
import pyqtgraph as pg
import numpy as np
import time
class CenteredArrowItem(pg.ArrowItem):
def paint(self, p, *args):
p.translate(-self.boundingRect().center())
pg.ArrowItem.paint(self, p, *args)
if __name__ == '__main__':
app = pg.QtGui.QApplication([])
window = pg.GraphicsWindow(size=(1280, 720))
window.setAntialiasing(True)
tracker = window.addPlot(title='Tracker')
while True:
for i in range(300):
arrow = CenteredArrowItem(angle=i, headLen=40, tipAngle=45, baseAngle=30)
arrow.setPos(i / 300, i / 300)
tracker.addItem(arrow)
app.processEvents()
time.sleep(0.02)
tracker.removeItem(arrow)
As you may noticed I'm adding and removing the arrow each iteration. This is because arrow.setStyle(angle=i) is not working as it does not update the rotation of the arrow (probably a bug).

A possible solution is to overwrite the paint method of ArrowItem and move the QPainter:
import numpy as np
from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg
class MyArrowItem(pg.ArrowItem):
def paint(self, p, *args):
p.translate(-self.boundingRect().center())
pg.ArrowItem.paint(self, p, *args)
app = QtGui.QApplication([])
w = QtGui.QMainWindow()
p = pg.PlotWidget()
p.showGrid(x = True, y = True, alpha = 0.3)
w.show()
w.resize(640, 480)
w.setCentralWidget(p)
w.setWindowTitle('pyqtgraph example: Arrow')
a = pg.ArrowItem(angle=-160, tipAngle=60, headLen=40, tailLen=40, tailWidth=20, pen={'color': 'w', 'width': 3}, brush='r')
b = MyArrowItem(angle=-160, tipAngle=60, headLen=40, tailLen=40, tailWidth=20, pen={'color': 'w', 'width': 3})
a.setPos(10,0)
b.setPos(10,0)
p.addItem(a)
p.addItem(b)
## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
As shown in the following figure, the red arrow is the default ArrowItem, and the blue is the offset, both are located in the same position with respect to the plot.
Update:
The problem is caused by the method that rotates the item used as the center of coordinates using the center of transformations by default, that is to say the (0, 0), we must move it:
import pyqtgraph as pg
import numpy as np
import time
from pyqtgraph.Qt import QtGui, QtCore
from pyqtgraph import functions as fn
class CenteredArrowItem(pg.ArrowItem):
def setStyle(self, **opts):
# http://www.pyqtgraph.org/documentation/_modules/pyqtgraph/graphicsItems/ArrowItem.html#ArrowItem.setStyle
self.opts.update(opts)
opt = dict([(k,self.opts[k]) for k in ['headLen', 'tipAngle', 'baseAngle', 'tailLen', 'tailWidth']])
tr = QtGui.QTransform()
path = fn.makeArrowPath(**opt)
tr.rotate(self.opts['angle'])
p = -path.boundingRect().center()
tr.translate(p.x(), p.y())
self.path = tr.map(path)
self.setPath(self.path)
self.setPen(fn.mkPen(self.opts['pen']))
self.setBrush(fn.mkBrush(self.opts['brush']))
if self.opts['pxMode']:
self.setFlags(self.flags() | self.ItemIgnoresTransformations)
else:
self.setFlags(self.flags() & ~self.ItemIgnoresTransformations)
if __name__ == '__main__':
app = pg.QtGui.QApplication([])
window = pg.GraphicsWindow(size=(1280, 720))
window.setAntialiasing(True)
tracker = window.addPlot(title='Tracker')
while True:
for i in range(300):
arrow = CenteredArrowItem(angle=i, headLen=40, tipAngle=45, baseAngle=30)
arrow.setPos(i / 300, i / 300)
tracker.addItem(arrow)
app.processEvents()
time.sleep(0.02)
tracker.removeItem(arrow)

After digging through the source code of pyqtgraph I ended up with a special function that suits my needs. I apply the translation when creating the arrow path, instead when rendering it. Fortunately this also solves the roation bug (for whatever reason).
Example:
import pyqtgraph as pg
import numpy as np
import time
import pyqtgraph.functions
class CenteredArrowItem(pg.ArrowItem):
def setData(self, x, y, angle):
self.opts['angle'] = angle
opt = dict([(k, self.opts[k]) for k in ['headLen', 'tipAngle', 'baseAngle', 'tailLen', 'tailWidth']])
path = pg.functions.makeArrowPath(**opt)
b = path.boundingRect()
tr = pg.QtGui.QTransform()
tr.rotate(angle)
tr.translate(-b.x() - b.width() / 2, -b.y() - b.height() / 2)
self.path = tr.map(path)
self.setPath(self.path)
self.setPos(x, y)
if __name__ == '__main__':
app = pg.QtGui.QApplication([])
window = pg.GraphicsWindow(size=(1280, 720))
window.setAntialiasing(True)
tracker = window.addPlot(title='Tracker')
arrow = CenteredArrowItem(headLen=40, tipAngle=45, baseAngle=30)
tracker.addItem(arrow)
tracker.addItem(pg.InfiniteLine(pos=(0,0), angle=45))
center = pg.ScatterPlotItem([], [], brush='r')
tracker.addItem(center)
while True:
for i in range(300):
arrow.setData(i, i, i)
center.setData([i], [i])
app.processEvents()
time.sleep(0.02)

Pyqt Graph Update with Callback

I am interested in real time graph. My aim is to update graph with another definition callback. I tried to debug but I don't see anythink after exec_() command. I tried to call update insteaded of Qtimer.
from pyqtgraph.Qt import QtGui, QtCore
import numpy as np
import pyqtgraph as pg
from multiprocessing import Process, Manager,Queue
def f(name):
app2 = QtGui.QApplication([])
win2 = pg.GraphicsWindow(title="Basic plotting examples")
win2.resize(1000,600)
win2.setWindowTitle('pyqtgraph example: Plotting')
p2 = win2.addPlot(title="Updating plot")
curve = p2.plot(pen='y')
def updateInProc(curve):
t = np.arange(0,3.0,0.01)
s = np.sin(2 * np.pi * t + updateInProc.i)
curve.setData(t,s)
updateInProc.i += 0.1
QtGui.QApplication.instance().exec_()
updateInProc.i = 0
timer = QtCore.QTimer()
timer.timeout.connect(lambda: updateInProc(curve))
timer.start(50)
if __name__ == '__main__':
m=f()
m
I want to use another definition like
def UpdateCallback():
for x in range(1,100):
m.updateInProc(x,time)
I deleted Qtimer then I tried to send data but I did not see at graph

turning grid on with AxisItem in pyqtgraph causes axis scaling to break

I am having trouble with AxisItem. As soon as I turn on both the x and y grid, the x-axis is no longer able to scale in and out with the zoom/pan function. Any ideas?
from PyQt4 import QtCore, QtGui
from pyqtgraph import Point
import pyqtgraph as pg
pg.setConfigOption('background', 'w')
pg.setConfigOption('foreground', 'k')
class plotClass(QtGui.QMainWindow):
def setupUi(self, MainWindow):
self.centralwidget = QtGui.QWidget(MainWindow)
MainWindow.resize(1900, 1000)
self.viewbox = pg.GraphicsView(MainWindow, useOpenGL=None, background='default')
self.viewbox.setGeometry(QtCore.QRect(0, 0, 1600, 1000))
self.layout = pg.GraphicsLayout()
self.viewbox.setCentralWidget(self.layout)
self.viewbox.show()
self.view = self.layout.addViewBox()
self.axis1 = pg.AxisItem('bottom', linkView=self.view, parent=self.layout)
self.axis2 = pg.AxisItem('right', linkView=self.view, parent=self.layout)
self.axis1.setGrid(255)
self.axis2.setGrid(255)
self.layout.addItem(self.axis1, row=1, col=0)
self.layout.addItem(self.axis2, row=0, col=1)
if __name__== "__main__":
import sys
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = plotClass()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())

Looking at your last comment, consider this option:
The pyqtgraph examples folder contains a "GraphItem.py" example which adds and displays a GraphItem object to a window via a ViewBox only. They don't use a grid however, so if you want to use a grid with a GraphItem, just add a PlotItem first (which has an associated ViewBox already... and you guessed it,...AxisItems for a grid!),... then get the ViewBox to add your GraphItems. The modified GraphItem.py would look like this (with the accompanying showGrid):
import pyqtgraph as pg
from pyqtgraph.Qt import QtCore, QtGui
import numpy as np
# Enable antialiasing for prettier plots
pg.setConfigOptions(antialias=True)
w = pg.GraphicsWindow()
w.setWindowTitle('pyqtgraph example: GraphItem')
### comment out their add of the viewbox
### since the PlotItem we're adding will have it's
### own ViewBox
#v = w.addViewBox()
pItem1 = w.addPlot() # this is our new PlotItem
v = pItem1.getViewBox() # get the PlotItem's ViewBox
v.setAspectLocked() # same as before
g = pg.GraphItem() # same as before
v.addItem(g) # same as before
pItem1.showGrid(x=True,y=True) # now we can turn on the grid
### remaining code is the same as their example
## Define positions of nodes
pos = np.array([
[0,0],
[10,0],
[0,10],
[10,10],
[5,5],
[15,5]
])
## Define the set of connections in the graph
adj = np.array([
[0,1],
[1,3],
[3,2],
[2,0],
[1,5],
[3,5],
])
## Define the symbol to use for each node (this is optional)
symbols = ['o','o','o','o','t','+']
## Define the line style for each connection (this is optional)
lines = np.array([
(255,0,0,255,1),
(255,0,255,255,2),
(255,0,255,255,3),
(255,255,0,255,2),
(255,0,0,255,1),
(255,255,255,255,4),
], dtype=[('red',np.ubyte),('green',np.ubyte),('blue',np.ubyte),('alpha',np.ubyte),('width',float)])
## Update the graph
g.setData(pos=pos, adj=adj, pen=lines, size=1, symbol=symbols, pxMode=False)
## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
I tested this and the scroll/zooming still worked after enabling the grid, so still not sure why doing it the other way DOESN'T work, but sometimes finding another way is the best answer :)

Adjusting colors of the surface plot item according to the signal values in pyqtgraph.opengl

Here is an attempt of doing a waterfall representation.
I need to express the signal(array) values(amplitudes/levels/densities) in different colors not in shades as done.
As I'm an algorithmic and signal processing eng. and not a software developer, I'm not familiar with the color maps and these stuff. So if someone could hep me out with the code for relating the colors with the signal values.
from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph.opengl as gl
import scipy.ndimage as ndi
import numpy as np
Nf = 90 # No. of frames
Ns = 100 # Signal length
app = QtGui.QApplication([])
w_SA = QtGui.QWidget(); w_SA.setFixedSize(400, 400)
# Create a GL View widget to display data
plt_SA1 = gl.GLViewWidget(w_SA); plt_SA1.move(10, 10); plt_SA1.resize(380, 380)
plt_SA1.setCameraPosition(elevation=90.0, azimuth=0.0, distance=70)
p1 = gl.GLSurfacePlotItem(shader='shaded', color=(0.5, 0.5, 1, 1), smooth=False)
p1.translate(-Nf/2, -Ns/2, 0)
plt_SA1.addItem(p1)
Arx = np.zeros([Nf, Ns])
def update():
global Arx
Arx = np.roll(Arx, 1, axis=0)
Arx[0] = ndi.gaussian_filter(np.random.normal(size=(1,Ns)), (1,1))
p1.setData(z=Arx)
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(30)
w_SA.show()
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()

Can you be more specific about how you want the image to be colored? If you don't need OpenGL, here is a simpler solution using pyqtgraph.ImageView. You can right-click on the gradient bar on the right side to change the lookup table used to color the image. There are also a variety of ways to set this table manually, depending on the desired effect.
from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph as pg
import scipy.ndimage as ndi
import numpy as np
Nf = 90 # No. of frames
Ns = 100 # Signal length
app = QtGui.QApplication([])
Arx = np.zeros([Nf, Ns])
win = pg.image(Arx)
win.view.setAspectLocked()
def update():
global Arx
Arx = np.roll(Arx, 1, axis=0)
Arx[0] = ndi.gaussian_filter(np.random.normal(size=(1,Ns)), (1, 1))
win.setImage(Arx.T, autoRange=False)
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(30)
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()