Re: [R] Comparing two matrices [Broadcast]

From: Liaw, Andy <andy_liaw_at_merck.com>
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.
>
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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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