QTableWidget display certain decimals like excel

Question

My question is about the way the QTableWidget displays the cell values.

I\'d like for the cell to show only three decimals when it\'s not being edited a

Answer 1

The solution is to use a delegate and override the paint method that is responsible for showing what looks in normal state, I have built the following class based on the above.

class FloatDelegate(QItemDelegate):
    def __init__(self, decimals, parent=None):
        QItemDelegate.__init__(self, parent=parent)
        self.nDecimals = decimals

    def paint(self, painter, option, index):
        value = index.model().data(index, Qt.EditRole)
        try:
            number = float(value)
            painter.drawText(option.rect, Qt.AlignLeft, "{:.{}f}".format(number, self.nDecimals))
        except :
            QItemDelegate.paint(self, painter, option, index)

In your case you should use it as follows:

self.TableWidget.setItemDelegate(FloatDelegate(3))

Example:

if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    w = QTableWidget()
    w.setColumnCount(8)
    w.setRowCount(8)
    for i in range(w.rowCount()):
        for j in range(w.columnCount()):
            number = (i+1)/(j+1)
            w.setItem(i, j, QTableWidgetItem(str(number)))
    w.setItemDelegate(FloatDelegate(3, w))
    w.show()
    sys.exit(app.exec_())

Screenshots:

Plus:

By Row o Column:

#only column 2
setItemDelegateForColumn(2, FloatDelegate(3))
#only row 2
setItemDelegateForRow(2, FloatDelegate(3))

If you want to apply only to cell 2,3

def paint(self, painter, option, index):
   if index.row() == 2 and index.column() == 3:
        value = index.model().data(index, Qt.EditRole)
        try:
            number = float(value)
            painter.drawText(option.rect, Qt.AlignLeft, "{:.{}f}".format(number, self.nDecimals))
        except :
            QItemDelegate.paint(self, painter, option, index)
    else:
        QItemDelegate.paint(self, painter, option, index)

Update:

• QStyledItemDelegate:

  class FloatDelegate(QStyledItemDelegate):
      def __init__(self, decimals, parent=None):
          super(FloatDelegate, self).__init__(parent=parent)
          self.nDecimals = decimals
  
      def displayText(self, value, locale):
          try:
              number = float(value)
          except ValueError:
              return super(FloatDelegate, self).displayText(value, locale)
          else:
              return locale.toString(number, format="f", precision=self.nDecimals)