Pyqtgraph: Synchronize Scaling Of Axes In Different Plots

I want to synchronize the X-Axis of several pyqtgraph plots. When the user rescales the X-Axis with mouse interactions (e.g. scroll-wheel while mouse on x-Axis) I want to assign th

Solution 1:

We need to use the sigRangeChanged signal and connect it to a slot, the problem is that the change of the range another item would generate the signal sigRangeChanged and so on generating an infinite loop, to solve this you must disconnect those signals before making the modifications and reconnect them to the final.

w1.sigRangeChanged.connect(onSigRangeChanged)
w2.sigRangeChanged.connect(onSigRangeChanged)

def onSigRangeChanged(r):
    w1.sigRangeChanged.disconnect(onSigRangeChanged)
    w2.sigRangeChanged.disconnect(onSigRangeChanged)
    if w1 == r:
        w2.setRange(xRange=r.getAxis('bottom').range)
    elif w2 == r:
        w1.setRange(xRange=r.getAxis('bottom').range)

    w1.sigRangeChanged.connect(onSigRangeChanged)
    w2.sigRangeChanged.connect(onSigRangeChanged)

Example:

import pyqtgraph as pg
from pyqtgraph.Qt import QtCore, QtGui
import numpy as np
from pyqtgraph.dockarea import *
import sys


def onSigRangeChanged(r):
    w1.sigRangeChanged.disconnect(onSigRangeChanged)
    w2.sigRangeChanged.disconnect(onSigRangeChanged)
    if w1==r:
        w2.setRange(xRange=r.getAxis('bottom').range)
    elif w2 == r:
        w1.setRange(xRange=r.getAxis('bottom').range)

    w1.sigRangeChanged.connect(onSigRangeChanged)
    w2.sigRangeChanged.connect(onSigRangeChanged)

app = QtGui.QApplication(sys.argv)

win = QtGui.QMainWindow()
area = DockArea()
win.setCentralWidget(area)
win.resize(1000,500)
win.setWindowTitle('pyqtgraph example: dockarea')


d1 = Dock("Dock1")
d2 = Dock("Dock2")
area.addDock(d1, 'bottom')
area.addDock(d2, 'bottom', d1)

w1 = pg.PlotWidget(title="Dock 1 plot")
it=w1.plot(np.random.normal(size=100))

d1.addWidget(w1)

w2 = pg.PlotWidget(title="Dock 2 plot")
w2.plot(np.random.normal(size=100))
d2.addWidget(w2)

w1.sigRangeChanged.connect(onSigRangeChanged)
w2.sigRangeChanged.connect(onSigRangeChanged)

win.show()

sys.exit(app.exec_())

Solution 2:

Better yet,

Instead of disconnecting then reconnecting signals, it is possible to use blockSignals.

here is a generic way to synchronize any number of plots :

syncedPlots = [w1, w2, w3] # put as many plots as you wishdefonSigRangeChanged(r):
    for g in syncedPlots:
        if g !=r :
            g.blockSignals(True)
            g.setRange(xRange=r.getAxis('bottom').range)
            g.blockSignals(False)

for g in syncedPlots:
     g.sigRangeChanged.connect(onSigRangeChanged)

Solution 3:

There is a better answer in this question:

Instead of connecting to the sigRangeChanged event we can directly link the axes scales by w2.setXLink(w1).