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[igraph] Documentation error

From: Gang Su
Subject: [igraph] Documentation error
Date: Tue, 22 Apr 2008 12:09:52 -0400
User-agent: Thunderbird (Windows/20080213)

In walktrap community, the documentation:

|membership| Numeric vector, the modularity score of the current community structure after each merge operation

here the membership should be 'modularity'


Gang Su wrote:
After another looking into the issue I found where the problem is
I have some string node ids began with a number, such as 76Character
I guess it's not allowed to have a string id began with letter?

I just prefixed a S_ to all the node names and it just worked.
If i don't prefix S_ to all nodes, the network may load, but functions like is.multiple will not work as it tells me invalid node ids.

Maybe the developers can take another look into this issue?


After looking into the issue it seems that it's some bug with
graph.edgelist function(i am not sure where is wrong).

if (is.character(el)) {
            names <- unique(as.character(t(el)))
            ids <- seq(names) - 1
            names(ids) <- names

#it fails right there, at the graph function
res <- graph(unname(ids[t(el)]), directed = directed)
            V(res)$name <- names

The bug is:
If I use graph.data.frame, it works fine.
If I use numeric ids for edgelist, it works fine.
If I use character ids for edgelist under 1500~2000 edges, it's fine.

If I load the entire dataset with graph.edgelist, it crashes, but it's
working with graph.data.frame.

I don't know whether this is a R bug or igraph bug.


Hi dear developers,

I have just migrated my working environment to a 64 bit system.
One weird issue i encountered is i tried to initialize a graph with
around 5k edges.
However, R will crash if I load around 3k edges.
For example,
if I use graph(el[1:1000,]), it is fine
if I use graph(el[1:3000,]), R will crash

I am now using R 2.6.2 with igraph. I not sure whether this is a igraph
bug or R bug for the 64 bit system. If you have used igraph on windows
XP 64 bit system please help!
thank you very much!


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