[R] Counting Frequencies in Data Frame

[Ista Zahn]

Hi,
Others will have fancier solutions, but is the way I would do it:

dat <- read.table(textConnection("1  2  3
1 aa ab ab
2 ab ab ab
3 aa aa aa
4 bb bb bb"), header=TRUE)
closeAllConnections()

countAB <- function(x) {
  aa <- length(which(x == "aa"))
  ab <- length(which(x == "ab"))
  bb <- length(which(x == "bb"))
  Result <- c(aa, ab, bb)
  return(Result)
}

Counts <- as.data.frame(t(apply(dat, 1, countAB)))
names(Counts) <- c("aa", "ab", "bb")

Best,
Ista

On Tuesday 18 May 2010 10:12:49 am M.Ribeiro wrote:
> Hi,
> I am sure there is an easy way to do it, but I can't find it.
> I have a data frame that has 15 columns and 7000 rows.
> 
> The only values inside the data.frame are "aa", "ab", "bb" as you can see
> an example bellow.
> 
>    1  2  3
> 1 aa ab ab
> 2 ab ab ab
> 3 aa aa aa
> 4 bb bb bb
> 
> What I would like to do, is to generate a vector (or another data.frame)
> with 7000 rows, and 3 columns. In the first column, the information about
> how many aa, the second about how many ab, and the third about how many bb
> are there in each line
>   aa  ab  bb
> 1  1   2   0
> 2  0   2   0
> 3  3   0   0
> 4  0   0   3
> 
> Thank you very much
> Cheers