The only problem is if there is more than one "1" in a row:
Here's the same idea, with the fix:
leadin1 <- function(mat=start.matrix){
nr <- nrow(mat)
nc <- ncol(mat)
pat <- rep(c(1,0),nr)
terminals <- apply(mat,1,function(x){match(1,x,nomatch=0)[1]})
copy.numbers <- as.numeric(rbind(terminals,nc-terminals))
out.mat <- matrix(rep(pat,copy.numbers),nr,nc,byrow=T)
out.mat
}
______________________
> Felipe,
> Use apply instead of a for loop. Here's an example of a function that
> should work. Note that apply returns a matrix that would need to be
> transposed.
>
> apply(matrix(c(
> 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> 0,0,0,0,1,2,3,0,0,0,0,0,0,0,0,0,0,
> 0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,
> 4,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> 2,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> 1,2,3,4,5,0,0,0,0,0,0,0,0,0,0,0,0,
> 0,0,0,0,0,0,1,2,3,4,5,0,0,0,0,0,0), ncol=17, byrow=T), 1,
> FUN = function(x) {
> one <- match(1, x, nomatch=0)
> return(c(rep(1,one), rep(0,length(x)-one)))
> })
>
> Dave
>
>
>
>
> Jordão, Felipe <Felipe.Jordao@moodys.com>
> Sent by: s-news-owner@lists.biostat.wustl.edu
> 07/20/2005 10:16 AM
>
> To: <s-news@lists.biostat.wustl.edu>
> cc:
> Subject: [S] matrix manipulation question
>
>
>
> Hi all,
>
> I have a matrix with some numbers (0:5). The number sequence usually
> begins with 1, but if starts in column 1 it can begin with another number.
> Once started it will go sequentially with no 0s in the middle, then go
> back to 0s. I want to do the following for each row:
>
> 1. If the sum of the row is zero, leave it as all 0s (i.e. it's blank to
> begin with, then leave it blank)
> 2. If the sum of the row is not zero, continue and do the following
> 3. Fill it with 1s until I hit the first "1", fill it with zeroes
> thereafter
>
> Here is an example:
>
> Start Matrix
> 00000000000000000
> 00001230000000000
> 00000000100000000
> 45000000000000000
> 23400000000000000
> 12345000000000000
> 00000012345000000
> ...
>
> End Matrix
> 00000000000000000
> 11111000000000000
> 11111111100000000
> 00000000000000000
> 00000000000000000
> 10000000000000000
> 11111110000000000
> ...
>
> It is a large enough matrix that I get a memory error if I use for loops
> (about 30x10000). I also need to keep the ordering of the rows, so if I
> start doing things like breaking it up in chunks it has to be put back
> properly.
>
> I appreciate any suggestions.
>
> thanks in advance,
> Felipe
>
>
>
>
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