Re: [igraph] Intersect graphs with different vertices

[Magnus Thor Torfason]

Hi Pete,

I'm glad that the code worked out for you, and sorry that I didn't 
respond earlier.

Anyway, to answer your question about adapting the code for directed 
graphs: No, there is no reason why this should not work with directed 
graphs. I simply had not tested them with directed graphs, and the check 
was only a matter of defensive programming. When the choice is between 
an error and a potentially unexpected result I tend to opt for an error 
(especially when the code can then be updated and tested with a given 
special case in mind).

I have actually now made these and a few other igraph utility functions 
available on my web page:

http://www.torfason.net/source-code/

If you are using the functions more or less as-is, it would probably be 
most useful to download them from there, since any updates or bug fixes 
would be reflected there.

And on that note, you mentioned that you added some attribute copying 
code. I'd very much like to incorporate any improvements into my code, 
if you're willing to share.

Best,
Magnus Thor

On 8/26/2010 1:39 PM, Peter Pirolli wrote:
> Hi:
>
> I came across your code in
>
> http://lists.nongnu.org/archive/html/igraph-help/2009-10/msg00087.html
>
> which looks to be exactly what I need (thank you)--except that I am working 
> with directed graphs. When I modified the relevant lines to permit directed 
> graphs and do the appropriate attribute copying, everything seems to work fine 
> for the simple examples that I tried. Can you tell me why you originally 
> restricted the functions to undirected graphs?
>
> --Pete