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'''
This module facilitates the process of creating ordered graph skeletons by topologically ordering them automatically.

'''

from external.libpgm.graphskeleton import GraphSkeleton

class OrderedSkeleton(GraphSkeleton):
    '''
    This class represents a graph skeleton (see :doc:`graphskeleton`) that is always topologically ordered.
    
    '''
    
    def __init__(self, graphskeleton=None):
        self.V = None
        '''A list of names of vertices'''
        self.E = None
        '''A list of [origin, destination] pairs of verties that constitute edges.'''

    def load(self, path):
        '''Loads a dictionary from a file located at *path* in the same manner as :doc:`graphskeleton`, but includes a step where it topologically orders the nodes.'''
    
        self.dictload(path)
        self.V = self.alldata["V"]
        self.E = self.alldata["E"]

        # topologically order
        self.toporder()

        # free unused memory
        del self.alldata
