From hb at maths.lth.se  Wed Nov 23 11:50:51 2005
From: hb at maths.lth.se (Henrik Bengtsson)
Date: Wed, 23 Nov 2005 21:50:51 +1100
Subject: [Rd] x[1,], x[1,,], x[1,,,], ...
Message-ID: <4384498B.1080401@maths.lth.se>

Hi,

is there a function in R already doing what I try to do below:

# Let 'x' be an array with *any* number of dimensions (>=1).
x <- array(1:24, dim=c(2,2,3,2))
...
x <- array(1:24, dim=c(4,3,2))

i <- 2:3

ndim <- length(dim(x))
if (ndim == 1)
   y <- x[i]
else if (ndim == 2)
   y <- x[i,]
else if (ndim == 3)
   y <- x[i,,]
else ...

and so on.  My current solution is

ndim <- length(dim(x))
args <- rep(",", ndim)
args[1] <- "i"
args <- paste(args, collapse="")
code <- paste("x[", args, "]", sep="")
expr <- parse(text=code)
y <- eval(expr)

ndim <- length(dim(x))
args <- rep(",", ndim)
args[1] <- "i"
args <- paste(args, collapse="")
code <- paste("x[", args, "]", sep="")
expr <- parse(text=code)
y <- eval(expr)

Is there another way I can do this in R that I have overlooked?

/Henrik



[Rd] x[1,], x[1,,], x[1,,,], ...
Henrik Bengtsson