[R] identifying which column an observation comes from?

arun smartpink111 at yahoo.com
Wed Oct 16 21:49:24 CEST 2013


ind <- which(mat==1,arr.ind=TRUE)[,2]
dat1<- data.frame(Code=names(ind),ind=ind,stringsAsFactors=FALSE)
 row.names(dat1) <- 1:nrow(dat1)

On Wednesday, October 16, 2013 3:29 PM, Karl Fetter <karl.fetter at gmail.com> wrote:

I have a matrix of samples (rows) and haplotypes (columns), where 0
indicates that a sample does not posses that columns haplotype and 1
indicates it does. So sample1 has 0's for every column, except the column
that represents haplotype X, and it has a 1.

I want a length(sample) x 2 dataframe that tells me which samples have what

I need some way of identifying for every row, where is the 1? And then
print that information in a new column so I can see what row and which

Here is an example of what I mean:

mat <- matrix(data = c(1,0,0,0,1,0,0,0,1), nrow = 3, byrow = T)

rownames(mat) <- c("AL", "MS", "FL")

> mat

   [,1] [,2] [,3]

AL    1    0    0

MS    0    1    0

FL    0    0    1

How can I make a data frame like this:

AL 1

MS 2

FL 3

Thanks for your ideas and time,


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