How can I have multiple left axisItems with the same alignment/position using pyqtgraph?

Question

I wonder if someone can help me out. I am trying to convert the MultiplePlotAxes.py example in pyqtgraph so that the all the axes are on the right side and aligned. Here is my code which I have added an extra plot:

"""
Demonstrates a way to put multiple axes around a single plot.
(This will eventually become a built-in feature of PlotItem)
"""
#import initExample  ## Add path to library (just for examples; you do not need this)

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

pg.mkQApp()

pw = pg.PlotWidget()
pw.show()
pw.setWindowTitle('pyqtgraph example: MultiplePlotAxes')
p1 = pw.plotItem
p1.setLabels(left='axis 1')

## create a new ViewBox, link the right axis to its coordinate system
p2 = pg.ViewBox()
p1.showAxis('right')
p1.scene().addItem(p2)
p1.getAxis('right').linkToView(p2)
p2.setXLink(p1)
p1.getAxis('right').setLabel('axis2', color='#0000ff')

## create third ViewBox.
## this time we need to create a new axis as well.
p3 = pg.ViewBox()
ax3 = pg.AxisItem('right')
p1.layout.addItem(ax3, 2, 3)
p1.scene().addItem(p3)
ax3.linkToView(p3)
p3.setXLink(p1)
ax3.setZValue(-10000)
ax3.setLabel('axis 3', color='#ff0000')

## create forth ViewBox.
## this time we need to create a new axis as well.
p4 = pg.ViewBox()
ax4 = pg.AxisItem('right')
p1.layout.addItem(ax4, 2, 4)
p1.scene().addItem(p4)
ax4.linkToView(p4)
p4.setXLink(p1)
ax4.setZValue(-10000)
ax4.setLabel('axis 4', color='#2EFEF7')

## Handle view resizing
def updateViews():
    ## view has resized; update auxiliary views to match
    global p1, p2, p3, p4
    p2.setGeometry(p1.vb.sceneBoundingRect())
    p3.setGeometry(p1.vb.sceneBoundingRect())
    p4.setGeometry(p1.vb.sceneBoundingRect())

    ## need to re-update linked axes since this was called
    ## incorrectly while views had different shapes.
    ## (probably this should be handled in ViewBox.resizeEvent)
    p2.linkedViewChanged(p1.vb, p2.XAxis)
    p3.linkedViewChanged(p1.vb, p3.XAxis)
    p4.linkedViewChanged(p1.vb, p4.XAxis)

updateViews()
p1.vb.sigResized.connect(updateViews)

p1.plot([1, 2, 4, 8, 16, 32])
p2.addItem(pg.PlotCurveItem([1, 2, 4, 9, 16, 32], pen='b'))
p3.addItem(pg.PlotCurveItem([1, 2, 4, 7, 16, 32], pen='r'))
p4.addItem(pg.PlotCurveItem([1, 3, 5, 7, 17, 32], pen='c'))

## 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_()

This produces the following picture which I have added a red arrow showing what I want to do.

Based on what I have been able to figure out I can do this using pg.GraphicsLayout(). However, the axisItem directly associated with plotItem and the created axisItems don't match because the one attached to the plotitem is smaller.

Here is a picture of what I believe is happening:

This is my problem as I want them to all align. In the attached code you can addItem(axes,2,1) to the right but it doesn't work on the left. Anyone know how I can do this?

Thanks in advance for any help you can provide.

Answer 1

I had this same issue, saw this post, was disappointed with the lack of an answer, but I finally did manage a fix so figured I would post here.

If you could post the code you have for the axis on the right, I could patch that up, but basically what I did was attach the bottom axis to a a row of its own.

self.main_pI = pg.PlotItem()
self.axis_bottom = self.main_pI.getAxis('bottom')
self.axis_bottom.setLabel('Time (seconds)', color='#ffffff')
self.layout.addItem(self.main_pI, row=1, col=2, rowspan=2)
self.layout.addItem(self.axis_bottom, row=3, col=2, rowspan=2)

I'm a noob at pyqtgraph so I'm sure I'm going to butcher this terminology, but I detach the 'bottom' axis, and reattach it to the layout, where it's on a row of its own.

Hope that helps.