PyQt - Implement a QAbstractTableModel for display in QTableView

Question

I would like to display a pandas data frame in a PyQt table. I have made some progress with this, but have not been able to correctly derive the Table Model class. Any help with this would be much appreciated.

** Note full example code here **

I am struggling to generate a valid QtCore.QAbstractTableModel derived class. Following on from a previous question about QItemDelegates I am trying to generate a table model from a Pandas DataFrame to insert real data. I have working example code here, but if I replace my TableModel with TableModel2 in the Widget class (ln 152) I cannot get the table to display.

class TableModel2(QtCore.QAbstractTableModel): 
    def __init__(self, parent=None, *args): 
        super(TableModel2, self).__init__()
        #QtCore.QAbstractTableModel.__init__(self, parent, *args)
        self.datatable = None
        self.headerdata = None
        self.dataFrame = None
        self.model = QtGui.QStandardItemModel(self)

    def update(self, dataIn):
        print 'Updating Model'
        self.datatable = dataIn
        print 'Datatable : {0}'.format(self.datatable)
        headers = dataIn.columns.values
        header_items = [
                    str(field)
                    for field in headers
        ]
        self.headerdata = header_items
        print 'Headers'
        print self.headerdata

        for i in range(len(dataIn.index.values)):
            for j in range(len(dataIn.columns.values)):
                #self.datatable.setItem(i,j,QtGui.QTableWidgetItem(str(df.iget_value(i, j))))
                self.model.setItem(i,j,QtGui.QStandardItem(str(dataIn.iget_value(i, j))))

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.datatable.index) 

    def columnCount(self, parent=QtCore.QModelIndex()):
        return len(self.datatable.columns.values) 

    def data(self, index, role=QtCore.Qt.DisplayRole): 
        if not index.isValid(): 
            return QtCore.QVariant()
        elif role != QtCore.Qt.DisplayRole: 
            return QtCore.QVariant() 
        #return QtCore.QVariant(self.model.data(index)) 
            return QtCore.QVariant(self.model.data(index)) 

    def headerData(self, col, orientation, role):
        if orientation == QtCore.Qt.Horizontal and role == QtCore.Qt.DisplayRole:
            return QtCore.QVariant()
        return QtCore.QVariant(self.headerdata[col])

    def setData(self, index, value, role=QtCore.Qt.DisplayRole):
        print "setData", index.row(), index.column(), value

    def flags(self, index):
        if (index.column() == 0):
            return QtCore.Qt.ItemIsEditable | QtCore.Qt.ItemIsEnabled
        else:
            return QtCore.Qt.ItemIsEnabled 

I am attempting to create the model and then add it to the view, like this:

class Widget(QtGui.QWidget):
    """
    A simple test widget to contain and own the model and table.
    """
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        l=QtGui.QVBoxLayout(self)
        cdf = self.get_data_frame()
        self._tm=TableModel(self)
        self._tm.update(cdf)
        self._tv=TableView(self)
        self._tv.setModel(self._tm)
        for row in range(0, self._tm.rowCount()):
            self._tv.openPersistentEditor(self._tm.index(row, 0))
        l.addWidget(self._tv)

    def get_data_frame(self):
        df = pd.DataFrame({'Name':['a','b','c','d'], 
        'First':[2.3,5.4,3.1,7.7], 'Last':[23.4,11.2,65.3,88.8], 'Class':[1,1,2,1], 'Valid':[True, True, True, False]})
        return df

Thanks for your attention!

Note : Edit 2 I have incorporated the QStandardItemModel into TableModel2. Also deleted the dataFrameToQtTable function after @mata's comment. This is getting a bit closer but still not working.

Answer 1

Ok I have figured this one out with the above suggestion and some help from the Rapid GUI book by Summerfield. There is no underlying model that exists in the QAbstractTableModel. Only three functions need be overridden, and the data may be stored in any user defined format, as long as it is returned in the data call.

A very simple implementation could be:

class TableModel(QtCore.QAbstractTableModel): 
    def __init__(self, parent=None, *args): 
        super(TableModel, self).__init__()
        self.datatable = None

    def update(self, dataIn):
        print 'Updating Model'
        self.datatable = dataIn
        print 'Datatable : {0}'.format(self.datatable)

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.datatable.index) 

    def columnCount(self, parent=QtCore.QModelIndex()):
        return len(self.datatable.columns.values) 

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if role == QtCore.Qt.DisplayRole:
            i = index.row()
            j = index.column()
            return '{0}'.format(self.datatable.iget_value(i, j))
        else:
            return QtCore.QVariant()

    def flags(self, index):
        return QtCore.Qt.ItemIsEnabled

This enables you to view any compatable data frame in a Qt view.

I have updated the Gist over here

This should get you going quickly if you also need to do this.

Answer 2

This is probably your problem:

def rowCount(self, parent=QtCore.QModelIndex()):
    if type(self.datatable) == pd.DataFrame:
    ...


def columnCount(self, parent=QtCore.QModelIndex()):
    if (self.datatable) == pd.DataFrame:
    ...

You set your datatable to a QTableWidget in dataFrameToQtTable, so it can't be a pd.DataFrame, your methods will always return 0.

Without the type check, you would have caught the problem immediately. Do you really want to silently ignore all cases where your type doesn't match (better let it raise an error if it doesn't follow the same interface you're expecting)? Typechecks are in most cases unnecessary.