A Chord plot is always drawn on a unit circle.

def get_extents(self, element, ranges, range_type='combined'):
        """
        A Chord plot is always drawn on a unit circle.
        """
        if range_type == 'extents':
            return element.nodes.extents
        xdim, ydim = element.nodes.kdims[:2]
        xpad = .05 if self.label_index is None else 0.25
        x0, x1 = ranges[xdim.name][range_type]
        y0, y1 = ranges[ydim.name][range_type]
        xdiff = (x1-x0)
        ydiff = (y1-y0)
        if self.label_position == 'right':
            x0, x1 = x0-(0.05*xdiff), x1+xpad*xdiff
        else:
            x0, x1 = x0-xpad*xdiff, x1+(0.05*xdiff)
        x0, x1 = max_range([xdim.range, (x0, x1)])
        y0, y1 = max_range([ydim.range, (y0-(0.05*ydiff), y1+(0.05*ydiff))])
        return (x0, y0, x1, y1)