如何在PyQT4表视图中突出显示每行中具有最高值的单元格

import sys
from PyQt4 import QtGui, QtCore

class TableModel(QtCore.QAbstractTableModel):
    def __init__(self, data):
        super(TableModel, self).__init__()
        self.data = data

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

    def columnCount(self, parent=QtCore.QModelIndex()):
        return len(self.data[0])

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if role == QtCore.Qt.DisplayRole:
            row = index.row()
            col = index.column()
            return str(self.data[row][col])

        if role == QtCore.Qt.BackgroundRole:
            row = index.row()
            max_value = max(self.data[row])
            col = index.column()
            if self.data[row][col] == max_value:
                return QtGui.QColor(QtCore.Qt.yellow)

        return None

class TableView(QtGui.QTableView):
    def __init__(self, data):
        super(TableView, self).__init__()
        self.model = TableModel(data)
        self.setModel(self.model)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    data = [
        [1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]
    ]
    tableView = TableView(data)
    tableView.show()
    sys.exit(app.exec_())