[R] Rearranging entries in a matrix

[Henrique Dallazuanna]

Try this also:

reshape(cbind(Id = 1:8, DF), v.names = 'y', timevar = 'z', direction =
'wide', idvar = 'Id')[-1]

On Thu, Feb 25, 2010 at 10:17 AM, Juliet Ndukum <jpntsang at yahoo.com> wrote:
> I have a matrix, called data. I used the code below to rearrange the data such that the first column remains the same, but the y value falls under either columns 2, 3 or 4, depending on the value of z. If z=1 for example, then the value of y will fall under column 2, if z=2, the value of y falls under column 3, and so on.
>
> data
>  x  y z
> [1,] 50 13 1
> [2,] 14  8 2
> [3,]  3  7 3
> [4,]  4 16 1
> [5,]  6  8 2
> [6,] 10  2 3
> [7,] 15 11 1
> [8,] 14  9 3
>> data1 <- data.frame(matrix(0, length(x), ncol(data)+1))
>> colnames(data1) <- c("x","y1","y2","y3")
>> data1$x <- data[,1]
>> data1$y1 <- apply(data, 1, function(x) (ifelse(x[3]==1,x[2],NA)))
>> data1$y2 <- apply(data, 1, function(x) (ifelse(x[3]==2,x[2],NA)))
>> data1$y3 <- apply(data, 1, function(x) (ifelse(x[3]==3,x[2],NA)))
>> data1
>   x y1 y2 y3
> 1 50 13 NA NA
> 2 14 NA  8 NA
> 3  3 NA NA  7
> 4  4 16 NA NA
> 5  6 NA  8 NA
> 6 10 NA NA  2
> 7 15 11 NA NA
> 8 14 NA NA  9
>
> I used the apply function (three times) to generate the output below, which is as I wish to have it.
> Can any one write for me a for loop that would produce the same results.
>
> Thanks in advance.
> JN
>
>
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O