[R] UNIX-like "cut" command in R

[Petr Savicky]

On Tue, May 03, 2011 at 01:39:49AM -0500, Mike Miller wrote:
> On Tue, 3 May 2011, Christian Schulz wrote:
> 
[...]
> >
> >x <- "this is a string"
> >unlist(strsplit(x," "))[c(1,4)]
> 
> 
> Thanks.  I did figure that one out a couple of messages back, but to get 
> it do behave like "cut -d' ' -f1,4", I had to add a paste command to 
> reassemble the parts:
> 
> paste(unlist(strsplit(x," "))[c(1,4)], collapse=" ")
> 
> Then I wasn't sure if I could do this to every element of a vector of 
> strings without looping -- I have to think not.

Try the following

  x <- c("this is a string", "this is a numeric")

  reassemble <- function(x, ind) paste(x[ind], collapse=" ")

  vapply(strsplit(x," "), reassemble, "character", c(1, 4))

  [1] "this string"  "this numeric"

Hope this helps.

Petr Savicky.