NetworkX Python – Class for Node vs. Multiple Attributes

graphpython

I've read through the NetworkX tutorial and documentation, but was unable to find real world answers for this question.

Usually when using NetworkX, I might use strings to define nodes, then set several attributes.

e.g.

G = nx.Graph()
G.add_node('John Doe', haircolor = 'brown')
G.node['John Doe'][age] = 22

However, it seems like declaring a class with members instead of attributes is better in practice, especially when there are many attributes and readability might be an issue.

class Person:
     name = None
     age = None

Person p
p.name = 'John Doe'
p.age = 22
G.add_node(p)

Could someone be kind enough to validate my reasoning? I lack the foresight to see if Networkx node/edge attributes would be preferable.

Best Answer

This doesn't answer your question. However. It seems necessary.

class Person:
     name = None
     age = None

Doesn't do what you're suggesting.

Those are two class-level attributes. They're emphatically not instance variables.

Also. You don't "declare" attributes at all. You don't declare them like that.

Person p isn't proper Python.

p= Person()
p.name = 'John Doe'
p.age = 22

This emphatically does not set the class level attributes created as part of the class. It creates additional instance-level attributes.

This may answer your question.

Networkx allows you to have any object associated with a node.

Feel free to do this

class Person( object ):
    def __init__( self, name, age ):
        self.name= name
        self.age= age

G.add_node('John Doe', data = Person( name='John Doe', age=22 ) )

Now you have all of your node data in a single object associated with the 'data' attribute.

For trivial name-value kinds of things, this is not obviously creating any real value.

But, if you have some node-specific method (rare in graph problems, but possible) then you'd have method functions associated with a node.

In graph theory problems, many of the algorithms work on the graph -- as a whole -- and you'll rarely find a use for a class with method functions.

Since the change is a trivial piece of syntax, it's probably simpler to start with

    G.add_node('John Doe', age=22 )

And migrate to 

    G.add_node('John Doe', data = Person( name='John Doe', age=22 ) )

when you absolutely need to.

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