Class Cluster

pattern/vector/__init__.py:1561–1597

# Hierarchical clustering is slow but the optimal solution guaranteed in O(len(vectors) ** 3).

class Cluster(list):
    
    def __init__(self, *args, **kwargs):
        """ A nested list of Cluster and Vector objects, 
            returned from hierarchical() clustering.
        """
        list.__init__(self, *args, **kwargs)
    
    @property
    def depth(self):
        """ Yields the maximum depth of nested clusters.
            Cluster((1, Cluster((2, Cluster((3, 4)))))).depth => 2.
        """
        return max([0] + [1 + n.depth for n in self if isinstance(n, Cluster)])
    
    def flatten(self, depth=1000):
        """ Flattens nested clusters to a list, down to the given depth.
            Cluster((1, Cluster((2, Cluster((3, 4)))))).flatten(1) => [1, 2, Cluster(3, 4)].
        """
        a = []
        for item in self:
            if isinstance(item, Cluster) and depth > 0:
                a.extend(item.flatten(depth-1))
            else:
                a.append(item)
        return a
    
    def traverse(self, visit=lambda cluster: None):
        """ Calls the given visit() function on this cluster and each nested cluster, breadth-first.
        """
        visit(self)
        for item in self:
            if isinstance(item, Cluster): 
                item.traverse(visit)

    def __repr__(self):
        return "Cluster(%s)" % list.__repr__(self)[1:-1]

def sequence(i=0, f=lambda i: i+1):
    """ Yields an infinite sequence, for example: