From: Liaw, Andy <andy_liaw_at_merck.com>

Date: Thu 06 Jul 2006 - 22:36:23 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jul 06 22:41:34 2006

Date: Thu 06 Jul 2006 - 22:36:23 EST

It might be a bit faster to do matrix indexing:

R> tbm <- as.matrix(tb) # turn it into a character matrix
R> tmat[cbind(match(tbm[,2], rownames(tmat)), match(tbm[,1],
colnames(tmat)))] <- 1

*> tmat
*

Apple Orange Mango Grape Star

A 1 1 1 0 0 O 1 1 0 0 0 M 0 0 1 0 0 G 0 0 0 0 0 S 1 1 1 0 0

**HTH,
**

Andy

From: Srinivas Iyyer

*>
**> hi:
**>
*

> I have matrix with dimensions(200 X 20,000). I have another

*> file, a tab-delim file where first column variables are row
**> names and second column variables are column names.
**>
**>
**> For instance:
**>
**> > tmat
**> Apple Orange Mango Grape Star
**> A 0 0 0 0 0
**> O 0 0 0 0 0
**> M 0 0 0 0 0
**> G 0 0 0 0 0
**> S 0 0 0 0 0
**>
**>
**>
**> > tb # tab- delim file.
**> V1 V2
**> 1 Apple S
**> 2 Apple A
**> 3 Apple O
**> 4 Orange A
**> 5 Orange O
**> 6 Orange S
**> 7 Mango M
**> 8 Mango A
**> 9 Mango S
**>
**>
**> I have to read each line of the 'tb' (tab delim file), take
**> the first variable, check if matches any rowname of the
**> matrix. Take the second variable of the row in and check if
**> it matches any column name. If so, put
**> 1 else leave it.
**>
**>
**> The following is a small piece of code that, I felt is a
**> solutions. However, since my original matrix and tab-delim
**> file is very very huge, I am not sure if it is really doing
**> the correct thing. Could any one please help me if I am doing
**> this correct.
**>
**>
**>
**> > for(i in 1:length(tb[,1])){
**> + r = tb[i,1]
**> + c = as.character(tb[i,2])
**> + tmat[rownames(tmat)==c,colnames(tmat)==r] <-1 }
**>
**>
**>
**> > tmat
**> Apple Orange Mango Grape Star
**> A 1 1 1 0 0
**> O 1 1 0 0 0
**> M 0 0 1 0 0
**> G 0 0 0 0 0
**> S 1 1 1 0 0
**>
**>
**>
**> Thanks.
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
**>
**>
*

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jul 06 22:41:34 2006

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