[Python] QtableView column sorting with floats formatted as strings

I need to use a custom QtableView in Python to display and format data.

The example app below shows a table with the first column of floats formatted as strings to get the proper number of decimals, the second column of floats displayed without formatting, and the third column contains strings.

When clicking on columns, I want to sort my data. This works fine for strings and floats (columns #2 and #3), but not for column #1 with formatted floats as strings where it's sorted alphabetically rather than numerically.

I've been googling for a while without finding a way to have something working with QtableView.

Any clue on how to get both floats sorting and decimal formatting?

Thanks & cheers

Stephane

import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtCore import *

# Table model
class TableModel(QtCore.QAbstractTableModel):
def __init__(self, data):
super(TableModel, self).__init__()
self._data = data
# Set columns headers
self.horizontalHeaders = [''] * 3
self.setHeaderData(0, Qt.Horizontal, "Col #1\nfloats as string")
self.setHeaderData(1, Qt.Horizontal, "Col #2\nfloats")
self.setHeaderData(2, Qt.Horizontal, "Col #3\nstrings")

def data(self, index, role):
value = self._data[index.row()][index.column()]
if role == Qt.DisplayRole:
# convert col #1 from floats to string to get proper number of decimal formatting
if index.column() == 0:
return '%.4f' % value
# otherwise display floats or strings for col #2 and #3
else:
return value

# Align values right
if role == Qt.TextAlignmentRole:
return Qt.AlignVCenter + Qt.AlignRight

def rowCount(self, index):
# The length of the outer list.
return len(self._data)

def columnCount(self, index):
# The following takes the first sub-list, and returns
# the length (only works if all rows are an equal length)
return len(self._data[0])

def setHeaderData(self, section, orientation, data, role=Qt.EditRole):
if orientation == Qt.Horizontal and role in (Qt.DisplayRole, Qt.EditRole):
try:
self.horizontalHeaders[section] = data
return True
except:
return False
return super().setHeaderData(section, orientation, data, role)

def headerData(self, section, orientation, role=Qt.DisplayRole):
if orientation == Qt.Horizontal and role == Qt.DisplayRole:
try:
return self.horizontalHeaders[section]
except:
pass
return super().headerData(section, orientation, role)


class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
# Create a TableView (not a TableWidget !!!)
self.table = QtWidgets.QTableView()

# sample data
data = [
[4.2, 9.6, 1],
[42.1, 0.0, 11],
[3.1, 5.55, 2],
[30.0, 3.55, 2222],
[7.99, 8.99, 33],
]

# Set table model
self.model = TableModel(data)
self.table.setModel(self.model)
self.setCentralWidget(self.table)

# Use proxy for column sorting
proxyModel = QSortFilterProxyModel()
proxyModel.setSourceModel(self.model)
self.table.setModel(proxyModel)
self.table.setSortingEnabled(True)

# hide vertical headers
self.table.verticalHeader().setVisible(False)

# format horizontal headers
stylesheet = "::section{Background-color:rgb(171,178,185);font-weight:bold}"
self.table.setStyleSheet(stylesheet)
self.table.setAlternatingRowColors(True)

if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.setMinimumSize(350, 250)
window.setWindowTitle('Sorting column example')
window.show()
app.exec_()

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