Re: [igraph] memory igraph

[Tamas Nepusz]

Dear Raghav,

> I want to create a large random graph, using erdos_renyi_game GNP:
> 
> N ~ 262144
> P ~ 0.5
This means that the resulting graph will have approximately 17 billion
edges. (262144^2 / 4). There's no way you can fit a graph of that size
into the memory of your computer.

> In any case I would like to generate a graph that is a group of erdos-renyi 
> graphs, with the groups connected randomly. There would be of the order 
> of 1000 nodes in each group and 256 groups. 
In that case, you are probably better off with igraph_preference_game.
This lets you specify a probability distribution of vertex types and a
preference matrix which defines the connection probability between
vertices of different types. If you want 256 groups, define 256 vertex
types with equal probabilities, and use a preference matrix which uses a
large connection probability between vertices of the same type and a
small probability between vertices of different types. That would
probably fit into the memory.

Or, alternatively, generate 256 Erdos-Renyi graphs using
igraph_erdos_renyi_game and then take the disjoint union.

-- 
Tamas