consecutive numbering of elements in a matrix
On Nov 21, 2009, at 3:25 PM, William Dunlap wrote:
-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of Jim Bouldin
Sent: Saturday, November 21, 2009 10:34 AM
To: r-help at r-project.org
Subject: [R] consecutive numbering of elements in a matrix
Within a very large matrix composed of a mix of values and
NAs, e.g, matrix A:
[,1] [,2] [,3]
[1,] 1 NA NA
[2,] 3 NA NA
[3,] 3 10 17
[4,] 4 12 18
[5,] 6 16 19
[6,] 6 22 20
[7,] 5 11 NA
mtx <- matrix(scan(textConnection(" 1 NA NA
3 NA NA
3 10 17
4 12 18
6 16 19
6 22 20
5 11 NA"), byrow=TRUE, ncol=3)
I need to be able to consecutively number, in new columns, the non-NA values within each column (i.e. A[1,1] A[3,2] and A[3,3] would all be set to one, and subsequent values in those columns would increase by one, until the last non-NA value is reached, if any).
Is this what you are looking for?
numberNonNAsInColumn <- function (A) {
for (i in seq_len(ncol(A))) {
isNotNA <- !is.na(A[, i])
A[isNotNA, i] <- seq_len(sum(isNotNA))
}
A
}
Semms like a simple apply would be sufficient:
apply(mtx, 2, function(x) cumsum(!is.na(x)))
[,1] [,2] [,3]
[1,] 1 0 0
[2,] 2 0 0
[3,] 3 1 1
[4,] 4 2 2
[5,] 5 3 3
[6,] 6 4 4
[7,] 7 5 4
Or if NA's are needed in the original NA positions:
> mt2 <- apply(mtx, 2, function(x) cumsum(!is.na(x)))
> is.na(mt2) <- is.na(mtx)
> mt2
[,1] [,2] [,3]
[1,] 1 NA NA
[2,] 2 NA NA
[3,] 3 1 1
[4,] 4 2 2
[5,] 5 3 3
[6,] 6 4 4
[7,] 7 5 NA
numberNonNAsInColumn(A)
[,1] [,2] [,3] [1,] 1 NA NA [2,] 2 NA NA [3,] 3 1 1 [4,] 4 2 2 [5,] 5 3 3 [6,] 6 4 4 [7,] 7 5 NA
numberNonNAsInColumn(cbind(c(101,NA,102,103,NA,NA,104),
c(1001,1002,1003,NA,1004,1005,1006)))
[,1] [,2]
[1,] 1 1
[2,] NA 2
[3,] 2 3
[4,] 3 NA
[5,] NA 4
[6,] NA 5
[7,] 4 6
I didn't know what you wanted to do if there were NA's
in the middle of a column.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
Any ideas? Thanks Jim Bouldin, PhD Research Ecologist Department of Plant Sciences, UC Davis Davis CA, 95616 530-554-1740
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______________________________________________ R-help at 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.
David Winsemius, MD Heritage Laboratories West Hartford, CT