This should get you started. It's not very fast but I think should do what
you want it to do. I used an Erdos-Renyi graph instead of star because your
neighbor constraint (#7) wouldn't have made sense then, as they are all
neighbors of one node. If the stopping point is when compartment "A" is
empty, and you want 15% of the nodes in "A" changed, the loop won't stop
(unless I did something wrong.
g <- erdos.renyi.game(100,
0.2)
V(g)$compartment <-
'A'
x <- sample(vcount(g),
10)
V(g)[x]$compartment <-
'B'
i <-
3
cnames <- c(LETTERS,
letters)
while (sum(V(g)$compartment == 'A') > 3)
{
x <- sample(which(V(g)$compartment == 'A'), round(0.15 *
sum(V(g)$compartment ==
'A')))
V(g)[x]$compartment <-
cnames[i]
nghbrs <- unique(unlist(adjacent_vertices(g,
x)))
y <- sample(nghbrs, round(0.12 *
length(nghbrs)))
if (length(y) > 0) V(g)[y]$compartment <- cnames[i +
1]
i <- i +
2
}
On Thu, May 11, 2017 at 9:40 AM, mario rossi <[email protected]>
wrote:
> Hi, R community!
>
> As you can read in the headline, i have a question for you about igraph.
>
> I need to make an algorithm that works as follow:
>
> 1) I start from a given network (for example a star: "g <-
> make_star(100)");
>
> 2) then, I assign to all nodes the same attribute (for example, all the
> nodes in the same compartment, that I call "A": "v(g)$compartment <-
> rep("A", 100)" );
>
> 3) I select a random number of nodes (for example: "sample(vcount(g),
> 10)");
>
> No problem with 1), 2) and 3)! But, please, can you help me with the
> following part of the algorithm?
>
> 4) I have to change the attribute to the randomly selected nodes (for
> example, if the result of the random sample of 10 nodes is
>
> sample(vcount(g),10)
>
> [1] 18 11 26 28 44 67 86 89 52 78,
>
> I have to change the compartment of nodes 18, 11, 26, ..., 78 from "A" to
> "B");
>
> 5) I have to randomly sampling, within the nodes that still in the
> compartment "A" (and not in "B") a given PERCENTAGE (and not a given
> number) of the nodes (in this first iteration, there are 90 nodes in the
> compartment "A", and I want to select, for example 15% of the 90 nodes).
>
> 6) I have to change the compartment of the just randomly selected nodes
> from "A" to a new compartment, called "C"; (Note that this will be a part
> of a "repeat until" loop, so I need to obtain an algorithm that
> automatically turn the compartment of the randomly selected nodes from "A"
> to "C").
>
> 7) I need to randomly sampling, AMONG THE NODES THAT ARE ADJACENT to those
> in compartment "C", a given percentage of them, for example 12%, and turn
> these just selected nodes into a new compartment, called "D".
>
> 8) If compartment "A" is empty, the algorithm stops. Otherwise, it return
> at point 5)
>
> End
>
>
>
> Thank you in advance, if you have time to help me.
>
> And sorry for my bad English.
>
> Mario Rossi
>
> _______________________________________________
> igraph-help mailing list
> [email protected]
> https://lists.nongnu.org/mailman/listinfo/igraph-help
>
>
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