CODEWITHSUNDEEP
pythongraphigraph
john
john

Reputation: 41

How to create an igraph object from a dictionary in Python

I'm using a dictionary to represent a graph in my Python program. I'm using the keys of the dictionary to represent vertices and the values to represent the adjacent nodes of each vertex. The dictionary currently looks like this:

{  
   'v1' : ['v2','v3'],
   'v2' : ['v1'],
   'v3' : ['v1','v4'],
   'v4' : ['v3']
    // And so on. 
}

Is there a straightforward way to create a new igraph object from this dictionary? If there's no easy way, what's the next-best option?

Upvotes: 1

Views: 3516

Answers (2)

Ebrahim Byagowi
Ebrahim Byagowi

Reputation: 11258

I did something like this which imports names of vertices to the graph also:

relations = {'v1': ['v2','v3'], 'v2': ['v1'], 'v3': ['v1','v4']}
g = igraph.Graph()
g.add_vertices(list(set(list(relations.keys()) + list([a for v in relations.values() for a in v]))))
g.add_edges([(v, a) for v in relations.keys() for a in relations[v]])

Upvotes: 1

eat
eat

Reputation: 7530

Well, according to the docs, it seems that igraph expects vertices encoded as integers. So you need to specify a mapping from your vertices to integers and then you could actually proceed for example like this:

G= {'v1': ['v2', 'v3'], 'v2': ['v1'], 'v3': ['v1', 'v4'], 'v4': ['v3']}
mvi= {'v1': 1, 'v2': 2, 'v3': 3, 'v4': 4}
graph= igraph.Graph(edges= [(mvi[v], mvi[a]) for v in G.keys() for a in G[v]])

Upvotes: 5

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