Re: [igraph] how to access edge weight in C

[Tamas Nepusz]

Hi,

> The *.ncol has three columns, the first two are the edge list, the last one 
> is the edge weight. After reading the graph, I want to access the weight of 
> each edge.
> Do Igraph provides an function to access the edge weight in C? I searched the 
> manual of C, and did not find one. 
You have to read the part of the documentation that is concerned with attribute 
handling:

http://igraph.sourceforge.net/doc/html/igraph-Attributes.html

Edge weights are assigned to a numeric edge attribute named "weight". In order 
to use attributes from C, you first have to turn on the C attribute handler 
before doing anything with igraph:

igraph_i_set_attribute_table(&igraph_cattribute_table);

After that, you can query numeric edge attributes using igraph_cattribute_EAN 
or igraph_cattribute_EANV (or their macro form: EAN and EANV). Read these pages 
as a start:

http://igraph.sourceforge.net/doc/html/ch09s02s01.html#igraph_cattribute_EAN
http://igraph.sourceforge.net/doc/html/ch09s02s01.html#igraph_cattribute_EANV

-- 
Tamas