graph.py 文件源码

def circular_layout(G, scale=1, center=None, dim=2, direction='CCW'):
    # dim=2 only
    """Position nodes on a circle.

    Parameters
    ----------
    G : NetworkX graph or list of nodes

    scale : float
        Scale factor for positions

    center : array-like or None
        Coordinate pair around which to center the layout.

    dim : int
        Dimension of layout, currently only dim=2 is supported

    Returns
    -------
    pos : dict
        A dictionary of positions keyed by node

    Examples
    --------
    >>> G = nx.path_graph(4)
    >>> pos = nx.circular_layout(G)

    Notes
    -----
    This algorithm currently only works in two dimensions and does not
    try to minimize edge crossings.

    """

    G, center = _process_params(G, center, dim)

    if len(G) == 0:
        pos = {}
    elif len(G) == 1:
        pos = {nx.utils.arbitrary_element(G): center}
    else:
        # Discard the extra angle since it matches 0 radians.
        theta = np.linspace(0, 1, len(G) + 1)[:-1] * 2 * np.pi
        theta = theta.astype(np.float32)
        if direction == 'CCW':
            pos = np.column_stack([np.cos(theta), np.sin(theta)])
        else:
            pos = np.column_stack([np.sin(theta), np.cos(theta)])
        pos = rescale_layout(pos, scale=scale) + center
        pos = dict(zip(G, pos))

    return pos