图的实现基本总结

1、采取邻接矩阵方式实现：

infinity = float("inf")

class AdjGraphError(TypeError):
    pass

class Graph: # basic graph class, using adjacent matrix
    def __init__(self, mat, unconn = 0):
        vnum1 = len(mat)
        for x in mat:
            if len(x) != vnum1: # Check square matrix
                raise ValueError("Argument for 'GraphA' is bad.")
        self.mat = [mat[i][:] for i in range(vnum1)]
        self.unconn = unconn
        self.vnum = vnum1

    def vertex_num(self):
        return self.vnum

    def add_edge(self, vi, vj, val = 1):
        assert 0 <= vi < self.vnum and 0 <= vj < self.vnum
        self.mat[vi][vj] = val

    def add_vertex(self):
        raise AdjGraphError(
            "Adj Matrix does not support 'add_vertex'")

    def get_edge(self, vi, vj):
        assert 0 <= vi < self.vnum and 0 <= vj < self.vnum
        return self.mat[vi][vj]

    def out_edges(self, vi):
        assert 0 <= vi < self.vnum
        return self._out_edges(self.mat, vi, self.unconn)

    @staticmethod
    def _out_edges(mat, vi, unconn):
        edges = []
        row = mat[vi]
        for i in range(len(row)):
            if row[i] != unconn:
                edges.append((i, row[i]))
        return edges

    def __str__(self):
        return "[\n" + "\n".join(map(str, self.mat)) + "\n]"\
               + "\nUnconnected: " + str(infinity)

2、采取邻接表方式

class GraphA(Graph):
    def __init__(self, mat, unconn = 0):
        vnum1 = len(mat)
        for x in mat:
            if len(x) != vnum1: # Check square matrix
                raise ValueError("Argument for 'GraphA' is bad.")
        self.mat = [Graph._out_edges(mat, i, unconn)
                        for i in range(vnum1)]
        self.vnum = vnum1
        self.unconn = unconn

    def add_vertex(self): # For new vertex, return an index allocated
        self.mat.append([])
        self.vnum += 1
        return self.vnum

    def add_edge(self, vi, vj, val = 1):
        assert 0 <= vi < self.vnum and 0 <= vj < self.vnum
        row = self.mat[vi]
        for i in range(len(row)):
            if row[i][0] == vj: # replace a value for mat[vi][vj]
                self.mat[vi][i] = (vj, val)
                return
            if row[i][0] > vj: break
            i += 1 # adjust for the new entry at the end
        self.mat[vi].insert(i, (vj, val))

    def get_edge(self, vi, vj):
        assert 0 <= vi < self.vnum and 0 <= vj < self.vnum
        for i, val in self.mat[vi]:
            if i == vj: return val
        return self.unconn

    def out_edges(self, vi):
        assert 0 <= vi < self.vnum
        return self.mat[vi]

3、运行结果：

if __name__ == '__main__':

#    g1 = Graph(10)
#    g2 = Graph(10, infinity)
#    print(str(g1))
#    print(str(g2))

    gmat = [[0,0,3,4],[2,0,0,0],[4,1,0,0],[2,0,1,0]]

    g3 = GraphA(gmat, 0)
    print(str(g3))
    g3.add_edge(0,3,5)
    print(str(g3))
    g3.add_edge(1,3,6)
    print(str(g3))
    g3.add_edge(3,1,9)
    print(str(g3))

runfile('/root/test/graph.py', wdir='/root/test')
[
[(2, 3), (3, 4)]
[(0, 2)]
[(0, 4), (1, 1)]
[(0, 2), (2, 1)]
]
Unconnected: inf
[
[(2, 3), (3, 5)]
[(0, 2)]
[(0, 4), (1, 1)]
[(0, 2), (2, 1)]
]
Unconnected: inf
[
[(2, 3), (3, 5)]
[(0, 2), (3, 6)]
[(0, 4), (1, 1)]
[(0, 2), (2, 1)]
]
Unconnected: inf
[
[(2, 3), (3, 5)]
[(0, 2), (3, 6)]
[(0, 4), (1, 1)]
[(0, 2), (1, 9), (2, 1)]
]
Unconnected: inf