PyQtGraph: How to name Bars in BarGraphItem

Question

I need to be able to create a graph in PyQtGraph that either displays strings on the x line like this:

Or inside of the bar itself like this:

These are my values:

y = [5.509, 5.509, 5.414, 5.414, 5.414, 5.289, 5.289, 5.289, 5.289, 5.289, 5.289, 5.289, 5.174, 5.174]
x = ['RUS', 'VET', 'OCO', 'MSC', 'MAZ', 'VER', 'HAM', 'BOT', 'GAS', 'STR', 'SAI', 'RAI', 'NOR', 'PER']

This is an example of what it could look like. "Note that this does not work"

# importing QtGui to use QIcon
from PyQt5.QtGui import *
from PyQt5.QtWidgets import QApplication
 
# importing pyqtgraph as pg
import pyqtgraph as pg
 
# importing QtCore and QtGui from the pyqtgraph module
from pyqtgraph.Qt import QtCore

 
# creating a pyqtgraph plot window
window = pg.plot()
 
# setting window geometry
window.setGeometry(100, 100, 600, 500)
 
# title for the plot window
title = "Test"
 
# setting window title to plot window
window.setWindowTitle(title)

y = [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
x = ['RUS', 'VET', 'OCO', 'MSC', 'MAZ', 'VER', 'HAM', 'BOT', 'GAS', 'STR', 'SAI', 'RAI', 'NOR', 'PER']

bargraph = pg.BarGraphItem(x=x, height=y, width=0.5)
window.addItem(bargraph)

# main method
if __name__ == '__main__':
     
    # importing system
    import sys
     
    # Start Qt event loop unless running in interactive mode or using
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QApplication.instance().exec_()

I need all the help I can get, since I haven't been able to find out anything myself.

score 2 · Accepted Answer · answered Apr 25 '22 at 23:36

This was a little more complicated than I thought. There are no examples for tick labels when you run the examples from the command line:

python -m pyqtgraph.examples

This question and the documentation for AxisItem provided the clues for how to set tick labels.

To make a proper bar chart, you have to pass in x values. And then you pass in replacement tick labels. For x values I just went from 1 to the number of labels: list(range(1, len(xlab)+1)). To get a reference to the x-axis, you use window.getAxis('bottom'). And finally, from the docs "The format for ticks looks like:"

[
    [ (majorTickValue1, majorTickString1), (majorTickValue2, majorTickString2), ... ],
    [ (minorTickValue1, minorTickString1), (minorTickValue2, minorTickString2), ... ],
    ...
]

Putting it all together we get:

# importing QtGui to use QIcon
from PyQt5.QtGui import *
from PyQt5.QtWidgets import QApplication

# importing pyqtgraph as pg
import pyqtgraph as pg

# importing QtCore and QtGui from the pyqtgraph module
from pyqtgraph.Qt import QtCore


# creating a pyqtgraph plot window
window = pg.plot()

# setting window geometry
window.setGeometry(100, 100, 600, 500)

# title for the plot window
title = "Test"

# setting window title to plot window
window.setWindowTitle(title)

y = [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
xlab = ['RUS', 'VET', 'OCO', 'MSC', 'MAZ', 'VER', 'HAM', 'BOT', 'GAS', 'STR', 'SAI', 'RAI', 'NOR', 'PER']
xval = list(range(1,len(xlab)+1))
print(xval)

ticks=[]
for i, item in enumerate(xlab):
    ticks.append( (xval[i], item) )
ticks = [ticks]

bargraph = pg.BarGraphItem(x=xval, height=y, width=0.5)
window.addItem(bargraph)
ax = window.getAxis('bottom')
ax.setTicks(ticks)

# main method
if __name__ == '__main__':

    # importing system
    import sys

    # Start Qt event loop unless running in interactive mode or using
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QApplication.instance().exec_()

and the plot is

It's worth pointing out that this exercise is significantly easier in Matplotlib. According to this example the equivalent plotting command in Matplotlib is a one-liner

win.bar(xlab, y)

PyQtGraph: How to name Bars in BarGraphItem

1 Answers1