In SAGE, '+' is used for union of sets. For example,
sage: a = Set([1,2])
sage: b = Set([2,3])
sage: a+b
{1, 2, 3}
Since currently, + is not defined for graphs, it'd be a natural choice.
--Mike
On 9/25/07, Jason Grout <[EMAIL PROTECTED]> wrote:
>
> I'm thinking more about how to make the Graph class easy to use. One
> thing that crops up is that the operations that combine graphs only
> combine two graphs at a time (e.g., g.union(h), where g and h are graphs).
>
> Is there a way to define an infix operator that would allow one to say:
>
> g union h union i union j union k?
>
> I could do it with something like:
>
> reduce(lambda x,y: x.union(y), [g,h,i,j,k])
>
> But that doesn't seem as clear as the infix things above.
>
> For reference, Mathematica allows an operator in backticks to be applied
> to its surrounding arguments, so the equivalent operation above would be:
>
> g `union` h `union` i `union` j `union` k
>
> And of course, you can set whether the operator is left-associative or
> right-associative.
>
> Of course, one solution is to use a for loop:
>
> newgraph=Graph()
> for graph in [g,h,i,j,k]:
> newgraph.union(graph)
>
> But that seems a lot clunkier than the infix expression above.
>
> I guess another solution is to return the new graph from the union, so
> that you could do:
>
> g.union(h).union(i).union(j)
>
> Thoughts?
>
> -Jason
>
>
> >
>
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