Hi Jim,
    Thank you for the response. Your suggestion will help me avoid the whole text to number conversion process that I perform using LookUp in excel. I will definitely give it a shot. But it still doesn't address the vector conversion since a graph file is drawn only using the vectors. Assuming that I use 'factor' to convert the characters to numbers, how do I convert these numbers into vectors?

Thanks,
Senthil




-----Original Message-----
From: jim holtman [mailto:jholtman@gmail.com]
Sent: Sat 7/19/2008 4:49 AM
To: Senthil Purushothaman
Cc: r-help@r-project.org
Subject: Re: [R] Calculating Betweenness - Efficiency problem
 
It would seem that you can output the initial file from EXCEL, read it
into R with 'read.csv' and then use 'factor' to convert the characters
for City1 and City2 to the numbers that you want to use.  Have you
tried this approach?

On Fri, Jul 18, 2008 at 3:51 PM, Senthil Purushothaman
<spurushothaman@lnxresearch.com> wrote:
> Hello,
>
> I am calculating 'Betweenness' of a large network using R. Currently, I have the node-node information (City1-City2) in an excel file, present in two columns where column A has City1 and column B has City2 that city1 is connected to. These are the steps that I go through to calculate betweenness of my network.
>
> a) Convert the City1-City2 (text) into Number1-Number2 in the excel file where every unique city has a unique number.
> b) Paste all the city-city information separated by comma into c(...) in the R GUI to obtain the corresponding vectors. As you can imagine this copy-paste operation takes a long time. Example: c(1,3,1,5,2,4,2,5). Just fyi, I have a text file that contains all nodes separated by comma based on the appropriate link information.
> c) Then, I create a graph file with the above vector.
> d) I use the graph file to calculate betweenness of my network.
>
> I am sure there must be a better, more efficient way to calculate betweenness. Ideally, I would like to just have the City1 - City2 (link) information in two columns in an excel file and calculate the betweenness from that file directly.
>
> Please provide an optimal solution for this problem. I appreciate your time and help.
>
> Thanks,
> Senthil
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?


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