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Re: [igraph] degree according to vertex attributes

From: Dominik Santner (CRIE)
Subject: Re: [igraph] degree according to vertex attributes
Date: Mon, 01 Oct 2012 12:25:19 +0200
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120907 Thunderbird/15.0.1

Hello Tamás,

I just solved my problems:

I solved the first problem by simply adding an argument (delete.vertices=F) to subgraph.edges.

The second problem was solved this way (maybe its not the most elegant way, but it works):

To receive a graph with empty labels I exported it and reimported it immediately:

write.graph(xxx, "temp.net", format="pajek")
xxx2 <- read.graph("temp.net"´, format="pajek")

Then I added the city attribute of the original graph to my new graph:

V(xxx2)$st_AMR <- V(xxx)$st_AMR

And everything works fine!

Thank you very much for your previous help!

Best regards,


Am 29.09.2012 11:56, schrieb Dominik Santner (CRIE):

thank you very much for your suggestion. Unfortunately there are two problems:

when using your example graph created by

g <- grg.game(100, 0.2)
V(g)$city <- LETTERS[(0:99 %/% 10) + 1]

I recieve a warning when doing


telling me that the two objects are not of the same length

[1] 96
[1] 100

the second problem occures when applying this procedure to my data:

in your example you use V(g)$city when doing

internal.edges <- which(V(g)$city[el[,1]] == V(g)$city[el[,2]])

whith the result:
  [1]   1   5   6   7   8 ...

when checking for
  [1] "A" "A" "A" "A" "A" ...

  [1] "A" "B" "B" "B" "A" "A" ...

everything is fine.

But with my dataset this happens:

internal.edges <- which(V(xxx)$st_AMR[el[,1]] == V(xxx)$st_AMR[el[,2]])

[1] "München" "Darmstadt" "Regensburg" "Halle" ...

  [1] NA NA NA NA NA ...

Maybe it has something to do with my vertex labels and/or my edge list, but I have no idea what it might be:

The edge list of your example:

     [,1] [,2]
[1,]    1    7
[2,]    1   11
[3,]    1   12
[4,]    1   13
[5,]    2    3
[6,]    2    4

The edge list of my dataset:

[1,] "Company A (6411000)"
[2,] "Company A (6411000)"
[3,] "Company A (6411000)"
[4,] "Company A (6411000)"
[5,] "Company A (6411000)"
[6,] "Company A (6411000)"
[1,] "University A (8416041)"
[2,] "University B (8416041)"
[3,] "Company B (5562024)"
[4,] "Company C (5358024)"
[5,] "Company D (5358024)"
[6,] "Company E (8215101)"

Best regards

Am 28.09.2012 23:44, schrieb Tamás Nepusz:

Suppose that the city is encoded in the "city" vertex attribute of the graph; for instance:

g <- grg.game(100, 0.2)
V(g)$city <- LETTERS[(0:99 %/% 10) + 1]
First, we get the edge list of the graph:

el <- get.edgelist(g)
Next, we select those edges (i.e. rows) from the edge list where the endpoints are in the same city:

internal.edges <- which(V(g)$city[el[,1]] == V(g)$city[el[,2]])
We then create a subgraph which consists of these edges only:

internal.graph <- subgraph.edges(g, internal.edges)
degree(internal.graph) will then give you how many friends each person has in the same city, and degree(g)-degree(internal.graph) will give you how many friends each person has in different cities.


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