def random_layout(G, dim=2, scale=1.0, center=None):
    """Position nodes uniformly at random.

    For every node, a position is generated by choosing each of dim
    coordinates uniformly at random on the default interval [0.0, 1.0),
    or on an interval of length `scale` centered at `center`.

    NumPy (http://scipy.org) is required for this function.

    Parameters
    ----------
    G : NetworkX graph or list of nodes
       A position will be assigned to every node in G.

    dim : int
       Dimension of layout.

    scale : float (default 1)
        Scale factor for positions

    center : array-like (default scale*0.5 in each dim)
       Coordinate around which to center the layout.

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

    Examples
    --------
    >>> G = nx.lollipop_graph(4, 3)
    >>> pos = nx.random_layout(G)
    """
    import numpy as np
    shape = len(G), dim
    pos = np.random.random(shape) * scale
    if center is not None:
        pos += np.asarray(center) - 0.5 * scale
    return dict(zip(G, pos))
