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getEdgeIndex -- finds the index of an edge in a HyperGraph

Synopsis

Description

This function returns the index of the edge of the (hyper)graph, where the ordering is determined by the internal ordering of the edges. Note that the internal order of the edges may not be preserved by methods that change the hypergraph (i.e., inducedHyperGraph, changeRing, hyperGraph(MonomialIdeal), etc.).

i1 : S = QQ[z_1..z_8];
 
i2 : h = hyperGraph {z_2*z_3*z_4,z_6*z_8,z_7*z_5,z_1*z_6*z_7,z_2*z_4*z_8}

o2 = HyperGraph{"edges" => {{z , z , z }, {z , z }, {z , z , z }, {z , z , z }, {z , z }}}
                              2   3   4     5   7     1   6   7     2   4   8     6   8
                "ring" => S
                "vertices" => {z , z , z , z , z , z , z , z }
                                1   2   3   4   5   6   7   8

o2 : HyperGraph
 
i3 : edges h

o3 = {{z , z , z }, {z , z }, {z , z , z }, {z , z , z }, {z , z }}
        2   3   4     5   7     1   6   7     2   4   8     6   8

o3 : List
 
i4 : getEdgeIndex (h,{z_2,z_4,z_8})  -- although entered last, edge is internally stored in 4th spot (counting begins at 0)

o4 = 3
 
i5 : getEdge(h,3)

o5 = {z , z , z }
       2   4   8

o5 : List
 
i6 : getEdgeIndex (h,{z_1,z_2}) -- not in the edge list

o6 = -1

See also

Ways to use getEdgeIndex :

For the programmer

The object getEdgeIndex is a method function.