can we use BFS and DFS algorithm in sagemath?
hello, I want to color the vertices of graphs using greedy or BFS algorithm. can do that in sagemath?
hello, I want to color the vertices of graphs using greedy or BFS algorithm. can do that in sagemath?
You can do BFS and DFS as follows:
sage: G = graphs.PetersenGraph()
sage: G.plot()
sage: list(G.breadth_first_search(start=3))
[3, 2, 4, 8, 1, 7, 0, 9, 5, 6]
sage: list(G.depth_first_search(start=3))
[3, 8, 6, 9, 7, 5, 0, 4, 1, 2]
What you get is the ordered list of vertices visited in both searches, starting from vertex 3.
Regarding coloring, i am not sure about your exact question. If you want to provide colors to the vertices to show the order of visit, you can try somthing like:
sage: G.plot(vertex_colors={rainbow(40)[i]:[v] for i,v in enumerate(G.breadth_first_search(start=3))})
With more striking example:
sage: G = graphs.Grid2dGraph(10,10)
sage: G.plot()
sage: G.plot(vertex_colors={rainbow(500)[i]:[v] for i,v in enumerate(G.breadth_first_search(start=(0,0)))})
sage: sage: G.plot(vertex_colors={rainbow(500)[i]:[v] for i,v in enumerate(G.depth_first_search(start=(0,0)))})
In SageMath, if you define a graph G
(for example G = Graph()
), then G.coloring?
gives the documentation of the coloring
method for G
, and G.coloring??
gives the source code.
Reading the documentation reveals two choices are offered: using the "dancing link algorithm" or using "mixed linear integer programming".
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Asked: 2019-01-09 12:18:58 +0100
Seen: 892 times
Last updated: Jan 11 '19
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