search.py 文件源码

def RandomGraph(nodes=range(10), min_links=2, width=400, height=300,
                                curvature=lambda: random.uniform(1.1, 1.5)):
    """Construct a random graph, with the specified nodes, and random links.
    The nodes are laid out randomly on a (width x height) rectangle.
    Then each node is connected to the min_links nearest neighbors.
    Because inverse links are added, some nodes will have more connections.
    The distance between nodes is the hypotenuse times curvature(),
    where curvature() defaults to a random number between 1.1 and 1.5."""
    g = UndirectedGraph()
    g.locations = {}
    ## Build the cities
    for node in nodes:
        g.locations[node] = (random.randrange(width), random.randrange(height))
    ## Build roads from each city to at least min_links nearest neighbors.
    for i in range(min_links):
        for node in nodes:
            if len(g.get(node)) < min_links:
                here = g.locations[node]
                def distance_to_node(n):
                    if n is node or g.get(node,n): return infinity
                    return distance(g.locations[n], here)
                neighbor = argmin(nodes, distance_to_node)
                d = distance(g.locations[neighbor], here) * curvature()
                g.connect(node, neighbor, int(d)) 
    return g