def columnCount(self, index=QModelIndex()):
        """DataFrame column number"""
        # Avoid a "Qt exception in virtual methods" generated in our
        # tests on Windows/Python 3.7
        # See PR 8910
        try:
            # This is done to implement series
            if len(self.df.shape) == 1:
                return 2
            elif self.total_cols <= self.cols_loaded:
                return self.total_cols
            else:
                return self.cols_loaded
        except AttributeError:
            return 0