[R] Trying to use pipes in R

[Duncan Murdoch]

On 12/09/2012 1:40 PM, Julio Sergio Santana wrote:
> Hi,
> I'm trying to use pipes in R. By now, I could launch the linux command "wc"
> (to count words from a text), but
> I don't know how to capture the results, say in a vector of chars...
> Here is the R code I'm trying:
>
> :> f <- pipe("wc", open="w")
> :> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
> :> close(f)
> :     3       6      31
>
> The result is just displayed but I couldn't put the result into a R
> variable.
> Do you have any comments on this?

The examples on the page don't show R both giving input and reading 
output from the same pipe.  I don't think you can set it up that way; R 
is only one process.  The usual approach is what is shown there:  write 
to a temporary file, then pipe the results of a command that works on 
that file back into R.  I guess you could also pipe some data into a 
command that writes a file, and then read that.

Duncan Murdoch