Dear Gabor, Thank you very much for the insights. I have been using the igraph package for my computations. But I did not know about graph.data.frame(). Thanks again for that. So I did run my data using the steps you had provided. Weirdly, even though the .csv file has approximately 300,000 records (remember that the file gets truncated to 65536 rows when opened in Excel 2003), not all of them are pulled in during the operation and the final betweenness list contains only ~1000+ records but it should be tens of thousands.
I know that you are a busy person. This problem seems to be a very different challenge. I am attaching the Test.csv file for your experiments. Thank you very much again. Best regards, Senthil (909) 267-0799 -----Original Message----- From: Gabor Csardi [mailto:[EMAIL PROTECTED] Sent: Monday, July 21, 2008 1:57 AM To: Senthil Purushothaman Cc: jim holtman; r-help@r-project.org Subject: Re: [R] Calculating Betweenness - Efficiency problem Senthil, you can try the 'igraph' package. Export your two-column Excel file as a .csv, use 'read.csv' to read that into R, then 'graph.data.frame' to create an igraph graph from it. Finally, call 'betweenness' on the graph. It is really just three/four lines, something like this: tab <- read.csv(...) g <- graph.data.frame(tab) bet <- betweenness(g) bet <- data.frame(city=V(g)$name, betweenness=bet) The last line creates a two column data frame with the betweenness score of each city. Best, Gabor On Sat, Jul 19, 2008 at 02:59:07PM -0700, Senthil Purushothaman wrote: > 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:[EMAIL PROTECTED] > 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 > <[EMAIL PROTECTED]> 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 > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > > > -- > Jim Holtman > Cincinnati, OH > +1 513 646 9390 > > What is the problem you are trying to solve? > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Csardi Gabor <[EMAIL PROTECTED]> UNIL DGM
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.