Convert dimension values to a dictionary.

        Returns a dictionary of column arrays along each dimension
        of the element.

        Args:
            dimensions: Dimensions to return as columns

        Returns:
            Dictionary of arrays for each dimension

def columns(self, dimensions=None):
        """Convert dimension values to a dictionary.

        Returns a dictionary of column arrays along each dimension
        of the element.

        Args:
            dimensions: Dimensions to return as columns

        Returns:
            Dictionary of arrays for each dimension
        """
        if dimensions is None:
            dimensions = self.dimensions()
        else:
            dimensions = [self.get_dimension(d, strict=True) for d in dimensions]
        return OrderedDict([(d.name, self.dimension_values(d)) for d in dimensions])