[R] how to read a file one line at a time?

[Peter Dalgaard BSA]

"Terry Westley" <twestley at buffalo.veridian.com> writes:

> Is there a way to read a file one line at a time?
> My file is potentially very large (multiple gigabytes)
> so I'd like to read and process one line at a time.
> 
> The only choices I see are:
> 
> 1) Direct the file to standard input and use readline(),
>    but then I have to parse the data columns myself.
> 
> 2) Call scan() with nlines=1 over and over again, incrementing
>    skip, but I suspect that it will read the whole file each
>    time.
> 
> Any suggestions?

Somewhere in the attic of my mind lies a plan to implement something
similar to the streams datatype of S4, but I don't think it will
happen soon.

I think the expedient way is to write a trio of short C routines for
dyn.loading and R wrappers: OpenFile, GetLine, CloseFile.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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