[R] loop, pipe connection, quote/unquote

Marco Grazzi grazzi at sssup.it
Wed Aug 2 12:56:55 CEST 2006

Hi all,

I have the following problem.
Inside R, I am trying to run a loop on several files. 
The data are stored in these files in a peculiar way, thus, at the same time I load the data, I would like to invoke a utility. I do this with "pipe". (The utility I am using is gbget from the package gbutils. It works correctly from shell, and it is not the problem.)
The problem is that from within pipe I do not know how to have the loop running. I guess I should manage to unquote the quotation mark inside the pipe for the loop to run, but I do not how to do it.
In the following examples, for instance, I would like pipe to interpret the "i" as the file.names of the loop specified above.

# specify the files on which I want to have the loop running
file.names <- system("ls ???.gz", intern=TRUE) 
# Start loop
for(i in file.names){
        dati     <- read.table(pipe("gbget  'i[160](1)' '[37](1)' '[145](1)' |gbget '()D' "))
	# [...] some statistical analysis follows [...]

Thanks for your help (hoping I manged to be enough clear), 


Marco Grazzi


PhD Candidate in Economics and Management
LEM-Sant'Anna School of Advanced Studies
Piazza Martiri della Liberta', 33
56127 Pisa, Italy
Tel. +39-050-883365 Fax +39-050-883344
Web site: https://mail.sssup.it/~grazzi

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