[R] how to extract consecutive subvetors of different lengths from an existing vector and create a matrix
arun
smartpink111 at yahoo.com
Tue Feb 25 16:57:58 CET 2014
Hi,
You could also do:
mat1 <- matrix(NA,ncol=max(n),nrow=length(n))
mat1[cbind(rep(seq_along(n),n),seq_len(sum(n))- rep(cumsum(c(0L,n[-length(n)])),n))] <- y
mat1
A.K.
On Tuesday, February 25, 2014 10:34 AM, arun <smartpink111 at yahoo.com> wrote:
Hi,
One way would be:
res <- t(sapply(split(y,rep(seq_along(n),n)),function(x) {if(length(x) < max(n)) c(x,rep(NA,max(n)-length(x))) else x}))
A.K.
Dear all,
my question regards how to subset an existing vector in
subvectors of different lengths and then create a matrix. See example
below.
I have vectors:
y<-c(1,1,1,0,0,1,1)
n<-c(3,2,2)
and I'd like to create the matrix A of the following form:
1 1 1
0 0 NA
1 1 NA
I'd like to "cut" y sequentially based on information in vector
n, that is, generating 3 subvectors (the first with the first 3 elements
of y, the second with the other 2 elements of y, and the last one with
the latter 2 elements of y) and creating a matrix A (with dimensions,
no.of rows=length(n), no. of col=max(n) and including NAs where
necessary.
Hope to have been clear.
Bex
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