Sage Reference Manual: Numerical Optimization - Mirrors

Sage Reference Manual: Numerical Optimization, Release 6.1.1
•params – params – An optional dict containing the edge parameters (see meth:add_edge). If
this parameter is not provided, all edges connecting u and v are deleted. Otherwise only edges with
matching parameters are deleted.
See Also:
delete_edges()
EXAMPLE:
sage: from sage.numerical.backends.glpk_graph_backend import GLPKGraphBackend
sage: gbe = GLPKGraphBackend()
sage: edges = [("A", "B", {"low":0.0, "cap":10.0, "cost":5})]
sage: edges.append(("A", "B", {"low":0.0, "cap":15.0, "cost":10}))
sage: edges.append(("B", "C", {"low":0.0, "cap":20.0, "cost":1}))
sage: edges.append(("B", "C", {"low":0.0, "cap":10.0, "cost":20}))
sage: gbe.add_edges(edges)
sage: gbe.delete_edge("A", "B")
sage: gbe.delete_edge("B", "C", {"low":0.0, "cap":10.0, "cost":20})
sage: print gbe.edges()[0][0], gbe.edges()[0][1], gbe.edges()[0][2][’cost’]
B C 1.0
delete_edges(edges)
Deletes edges from the graph.
Non existing edges are ignored.
INPUT:
•edges – An iterable container of edges.
See Also:
delete_edge()
EXAMPLE:
sage: from sage.numerical.backends.glpk_graph_backend import GLPKGraphBackend
sage: gbe = GLPKGraphBackend()
sage: edges = [("A", "B", {"low":0.0, "cap":10.0, "cost":5})]
sage: edges.append(("A", "B", {"low":0.0, "cap":15.0, "cost":10}))
sage: edges.append(("B", "C", {"low":0.0, "cap":20.0, "cost":1}))
sage: edges.append(("B", "C", {"low":0.0, "cap":10.0, "cost":20}))
sage: gbe.add_edges(edges)
sage: gbe.delete_edges(edges[1:])
sage: len(gbe.edges())
1
sage: print gbe.edges()[0][0], gbe.edges()[0][1], gbe.edges()[0][2][’cap’]
A B 10.0
delete_vertex(vert)
Removes a vertex from the graph.
Trying to delete a non existing vertex will raise an exception.
INPUT:
•vert – The name (as str) of the vertex to delete.
EXAMPLE:
sage: from sage.numerical.backends.glpk_graph_backend import GLPKGraphBackend
sage: gbe = GLPKGraphBackend()
sage: verts = ["A", "D"]
5.3. GLPK Backend for access to GLPK graph functions 85