using strings and floats in QTableView, QStandardItemModel, QStandardItem

[consumererik]

I'm trying to use a QTableView, with a QStandardItemModel. The QStandardItemModel expects QStardardItem objects to populate "table cells", and the constructor for QStandardItem only accepts QStrings, or just str in python.
My data is both strings and floats. I noticed the documentation says you can subclass QStandardItem to "define new types for them". Here is my attempt at subclassing QStandardItem:

from PyQt5.QtGui import QStandardItem
class TableItemFloat(QStandardItem):
    def __init__(self, val):
        super().__init__(str(val))
        return
    
    def type(self):
        return 1000

But this clearly isn't what I'm meant to do. Do I need to reimplement setData() ? Do I need to have a instance attribute like self.data = val? What about setItem() the model uses? Do I need to subclass the model too? Here is what I'm experimenting with:

class Example(QWidget):
    
    def __init__(self):
        super().__init__()
        
        self.setGeometry(300, 300, 400, 300)
        self.setWindowTitle("QTableView")
        self.initData()
        self.initUI()
        
    def initData(self):
    
        #data = [['1','2',3, 'None'],["blue", "green", "yellow", "red"]]
        data = [[1,2,3],[4,3,5]]
        self.model = QStandardItemModel(10, 6)
        
        row = 0
        col = 0
        
        for i in data:
            for j in i:
                print(j)
                item = TableItemFloat(j)
                self.model.setItem(row, col, j)
                row = row + 1
            col = col +1
            row = 0
            
    def initUI(self):
             
        self.tv = QTableView(self)
        self.tv.setModel(self.model)
        vbox = QVBoxLayout()
        vbox.addWidget(self.tv) 
        self.setLayout(vbox)  

app = QApplication([])
ex = Example()
ex.show()
sys.exit(app.exec_())