thanks, I tried david suggestion and it's correct now :

edges = [(1,2), (1,3), (1,4),
    (2,3), (2,4), (2,5), (2, 6),
    (3,4), (3,5), (3,6), (3,7),
    (4,6), (4,7), (5,6), (6,7)]
Gamma = Graph(edges)
Gamma.show()


Meanwhile I made it too with networkx to compare :

import networkx as nx
import matplotlib.pyplot as plt
G = nx.Graph()
edges = [(1,2), (1,3), (1,4),
    (2,3), (2,4), (2,5), (2, 6),
    (3,4), (3,5), (3,6), (3,7),
    (4,6), (4,7), (5,6), (6,7)]
G.add_edges_from(edges)
nx.draw_networkx(G)
limits = plt.axis('off')
plt.show(G)



Le 07/04/2018 à 15:09, Jan Groenewald a écrit :
Hi

On 7 April 2018 at 14:52, Henri Girard <[email protected] <mailto:[email protected]>> wrote:

    I made this graph (meaning a fano's plane) but I have the zero
    outside the graph ?

    I don't understand why ? someone could explain ?

    My adjacency_matrix is 8 but shouldn't be 7 ?

    g=Graph(7)
    edges = [(1,2), (1,3), (1,4),
        (2,3), (2,4), (2,5), (2, 6),
        (3,4), (3,5), (3,6), (3,7),
        (4,6), (4,7), (5,6), (6,7)]
    g.add_edge(1,2),g.add_edge(1,3),g.add_edge(1,4),g.add_edge(2,3),
    g.add_edge(2,4),g.add_edge(2,5),g.add_edge(2,6),g.add_edge(3,4),
    g.add_edge(3,5),g.add_edge(3,6),g.add_edge(3,7),g.add_edge(4,6),
    g.add_edge(4,7),g.add_edge(5,6),g.add_edge(6,7)
    g.show()
    g.adjacency_matrix(),g.incidence_matrix()

    Best



Graph? shows

      2. "Graph(5)" -- return an edgeless graph on the 5 vertices
         0,...,4.

      3. "Graph([list_of_vertices,list_of_edges])" -- returns a
         graph with given vertices/edges.

         To bypass auto-detection, prefer the more explicit
         "Graph([V,E],format='vertices_and_edges')".

      4. "Graph(list_of_edges)" -- return a graph with a given list
         of edges (see documentation of "add_edges()").

         To bypass auto-detection, prefer the more explicit "Graph(L,
         format='list_of_edges')".

      5. "Graph({1:[2,3,4],3:[4]})" -- return a graph by
         associating to each vertex the list of its neighbors.

         To bypass auto-detection, prefer the more explicit "Graph(D,
         format='dict_of_lists')".

so it seems correct, and there are alternatives if you prefer 1..8 instead of 0..7.

Regards,
Jan





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