Changing labels of a graph and access edge thickness

graph

asked 2021-01-05 12:27:03 +0100

Cyrille
1407 ●34 ●76 ●138

updated 2021-01-05 16:14:19 +0100

slelievre
17704 ●22 ●160 ●350 http://carva.org/samue...

This is a graph. But now I want the vertices labeled with {'A', 'B', 'C'} or some names, and colored. And I have not seen an option for specifying the thickness of edges and of the arrow head.

Working with this example adapted from the documentation:

D = DiGraph({0: [0, 1], 1: [2], 2: [3]}, loops=True)
D.show(edge_colors={(0, 1, 1): [(0, 1), (2, 3)]})

I have been surprised not to be allowed to put edge_colors inside show() in my case, but this is of less importance since there is another way.

Of more importance, in graph options I have not seen any command for the thickness of the edges and of the arrow head.

One more time thanks for your help.

edit retag flag offensive close merge delete

add a comment

1

answered 2021-01-05 12:51:49 +0100

tmonteil
27423 ●31 ●204 ●517 http://wiki.sagemath.o...

updated 2021-01-05 12:59:27 +0100

You can relabel the graph with the relabel method:

sage: D.relabel(['A','B','C','D'])

check

sage: D.relabel?

for more options.

Regarding coloring the vertices, you can do

sage: D.show(vertex_colors={'blue':[0,2],'green':[1],'black':[3]})

see

sage: D.plot?

for more plotting options.

There might be one somewhere, but i do not see an edge-thickness option either in the documentation. However, looking into the source code of the GraphPlot class:

sage: from sage.graphs.graph_plot import GraphPlot
sage: GraphPlot??

It seems that you can do:

sage: D.show(edge_thickness=4)

Also, there is a edge_style option which can be one of 'solid', 'dashed', 'dotted', dashdot', 'None'.

edit flag offensive delete link

Comments

Thanks. But D.relabel() generates an error in my case. Also ?relabel() gives "Object relabel() not found."

Cyrille ( 2021-01-05 13:26:17 +0100 )edit

Which version of sagemath are you using and what's the error message ?

sage: D = DiGraph({0:[0,1], 1:[2], 2:[3]}, loops=True)                                                                                              
sage: D.relabel(['A','B','C','D'])                                                                                                                  
sage: D.edges(labels=False)                                                                                                                         
[('A', 'A'), ('A', 'B'), ('B', 'C'), ('C', 'D')]

David Coudert ( 2021-01-05 13:32:37 +0100 )edit

Sorry but this

D = DiGraph( { 0: [1, 2, 3, 4], 1: [2, 3, 4], 2: [3, 4], 3: [4], 4:[]})
D.relabel(['A','B','C','D'])
vc = {'#51c8f1':[0,1,2,3,4]}
ec = {'#ad8393':[(0,1),(0,4)],'#4c75a3':[(2,4),(3,4)]}
D.edges(labels=False)

generates this

<repr(<sage.graphs.views.EdgesView at 0x6ffec68c7110>) failed: TypeError: '<' not supported between instances of 'int' and 'str'>

Cyrille ( 2021-01-05 14:32:26 +0100 )edit

My version is sage 9.2

Cyrille ( 2021-01-05 16:48:27 +0100 )edit

Because the vertices of your new graph are 'A', 'B', 'C', 'D', 4 and since 'A' and 4 are not comparable (a string vs an integer), apparently, you need to add sort=False option to prevent sorting :

sage: D.edges(labels=False, sort=False)
[('A', 'B'), ('A', 'C'), ('A', 'D'), ('A', 4), ('B', 'C'), ('B', 'D'), ('B', 4), ('C', 'D'), ('C', 4), ('D', 4)]

I would say that raising an error in such case is a kind of bug.