Multiple x or y axes with the same axisitem alignment

[RC]

Hi Guys

I'm trying to generate a viewing program for some data. I wanted the ability to plot multiple x or y axes together and position these on the top, bottom, left or right axes. This I found out how to do using someones code shown below

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

pg.mkQApp()

# Axis
a2 = pg.AxisItem("left")
a3 = pg.AxisItem("left")
a4 = pg.AxisItem("left")
a5 = pg.AxisItem("left")
a6 = pg.AxisItem("left")

# ViewBoxes
v2 = pg.ViewBox()
v3 = pg.ViewBox()
v4 = pg.ViewBox()
v5 = pg.ViewBox()
v6 = pg.ViewBox()

# main view
pw = pg.GraphicsView()
pw.setWindowTitle('pyqtgraph example: multiple y-axis')
pw.show()

# layout
l = pg.GraphicsLayout()
pw.setCentralWidget(l)

# add axis to layout
## watch the col parameter here for the position
l.addItem(a2, row=2, col=5, rowspan=1, colspan=1)
l.addItem(a3, row=2, col=4, rowspan=1, colspan=1)
l.addItem(a4, row=2, col=3, rowspan=1, colspan=1)
l.addItem(a5, row=2, col=2, rowspan=1, colspan=1)
l.addItem(a6, row=2, col=1, rowspan=1, colspan=1)

# plotitem and viewbox
## at least one plotitem is used whioch holds its own viewbox and left axis
pI = pg.PlotItem()
v1 = pI.vb  # reference to viewbox of the plotitem
l.addItem(pI, row=2, col=6, rowspan=1, colspan=1)  # add plotitem to layout

# add viewboxes to layout
l.scene().addItem(v2)
l.scene().addItem(v3)
l.scene().addItem(v4)
l.scene().addItem(v5)
l.scene().addItem(v6)

# link axis with viewboxes
a2.linkToView(v2)
a3.linkToView(v3)
a4.linkToView(v4)
a5.linkToView(v5)
a6.linkToView(v6)

# link viewboxes
v2.setXLink(v1)
v3.setXLink(v2)
v4.setXLink(v3)
v5.setXLink(v4)
v6.setXLink(v5)

# axes labels
pI.getAxis("left").setLabel('axis 1 in ViewBox of PlotItem', color='#FFFFFF')
a2.setLabel('axis 2 in Viewbox 2', color='#2E2EFE')
a3.setLabel('axis 3 in Viewbox 3', color='#2EFEF7')
a4.setLabel('axis 4 in Viewbox 4', color='#2EFE2E')
a5.setLabel('axis 5 in Viewbox 5', color='#FFFF00')
a6.setLabel('axis 6 in Viewbox 6', color='#FE2E64')


# slot: update view when resized
def updateViews():
    v2.setGeometry(v1.sceneBoundingRect())
    v3.setGeometry(v1.sceneBoundingRect())
    v4.setGeometry(v1.sceneBoundingRect())
    v5.setGeometry(v1.sceneBoundingRect())
    v6.setGeometry(v1.sceneBoundingRect())


# data
x = [1, 2, 3, 4, 5, 6]
y1 = [0, 4, 6, 8, 10, 4]
y2 = [0, 5, 7, 9, 11, 3]
y3 = [0, 1, 2, 3, 4, 12]
y4 = [0, 8, 0.3, 0.4, 2, 5]
y5 = [0, 1, 6, 4, 2, 1]
y6 = [0, 0.2, 0.3, 0.4, 0.5, 0.6]

# plot
v1.addItem(pg.PlotCurveItem(x, y1, pen='#FFFFFF'))
v2.addItem(pg.PlotCurveItem(x, y2, pen='#2E2EFE'))
v3.addItem(pg.PlotCurveItem(x, y3, pen='#2EFEF7'))
v4.addItem(pg.PlotCurveItem(x, y4, pen='#2EFE2E'))
v5.addItem(pg.PlotCurveItem(x, y5, pen='#FFFF00'))
v6.addItem(pg.PlotCurveItem(x, y6, pen='#FE2E64'))

# updates when resized
v1.sigResized.connect(updateViews)

# autorange once to fit views at start
v2.enableAutoRange(axis=pg.ViewBox.XYAxes, enable=True)
v3.enableAutoRange(axis=pg.ViewBox.XYAxes, enable=True)
v4.enableAutoRange(axis=pg.ViewBox.XYAxes, enable=True)
v5.enableAutoRange(axis=pg.ViewBox.XYAxes, enable=True)
v6.enableAutoRange(axis=pg.ViewBox.XYAxes, enable=True)

updateViews()

if __name__ == '__main__':
    import sys

    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

My problem is when I run the code the axes on the left side dont align perfectly. I.e the 0 for all axes should be at the same point as this is common to all of them. However, what I get is shown in the attachment. Anyone know how to get around this problem?

Thanks in advance for any help you can provide on this.

[RC]

I have figured something out that is not perfect but is pretty close. by splitting off the axis and adding an extra axis item to the bottom in the appropriate space and blanking it out I have come up with this. All lines line up but not perfectly with the y-axis but close enough to get away with it. Here is the code and results

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

pg.mkQApp()

# Axis
a2 = pg.AxisItem("left")
a3 = pg.AxisItem("left")
a4 = pg.AxisItem("left")  
a5 = pg.AxisItem("left")
a6 = pg.AxisItem("left")

# ViewBoxes
v2 = pg.ViewBox()
v3 = pg.ViewBox()
v4 = pg.ViewBox()
v5 = pg.ViewBox()
v6 = pg.ViewBox()

# main view
pw = pg.GraphicsView()
pw.setWindowTitle('pyqtgraph example: multiple y-axis')
pw.show()

# layout
l = pg.GraphicsLayout()
pw.setCentralWidget(l)

# add axis to layout
## watch the col parameter here for the position

l.addItem(a2, row=1, col=5, rowspan=1, colspan=1)
l.addItem(a3, row=1, col=4, rowspan=1, colspan=1)
l.addItem(a4, row=1, col=3, rowspan=1, colspan=1)
l.addItem(a5, row=1, col=2, rowspan=1, colspan=1)
l.addItem(a6, row=1, col=1, rowspan=1, colspan=1)

# Blank axis used for aligning things
ax = pg.AxisItem(orientation='bottom')
ax.setPen('#000000')
pos = (2,2)
l.addItem(ax, *pos)

# plotitem and viewbox
## at least one plotitem is used which holds its own viewbox and left axis

pI = pg.PlotItem()
v1 = pI.vb  # reference to viewbox of the plotitem

l.addItem(pI, row=1, col=8, rowspan=2, colspan=1)  # add plotitem to layout

# split off 1st axis and put to side
pI.axis_left = pI.getAxis('left')
pos = (1,7)
l.addItem(pI.axis_left, *pos)