[R] scan

[S.McClatchie]

On 14 Mar 01,, Heberto Ghezzo wrote (re: [R] scan): 

> Hello, I have a problem. I have to read a HUGE file which has to be 
> line processed, so I would like to use scan like
> p <- scan(pfile,what=c(0,0,0,"",0,""),nlines=1)
> but it continues to read the first line, so I have to add a skip and
> increment the skip after each read. It takes forever to read a test file
> of 1 Mb, the real one is in 60's Mb Is there a way to read line by line an
> ASCII file without having to reread the part already read? Thanks for any
> help.
> 
> R. Heberto Ghezzo  Ph.D.
> Meakins-Christie Labs
> McGill University

Bonjour Heberto

Just one option is to use read.table or read.csv: 

e.g. for a batch of files called name1A.txt, name1B.txt in the directory 
h:/data/nov99_tan9913/opc/ having 2 columns called code and value you 
could sequentially read the files

 dir <- c('h:/data/nov99_tan9913/opc/')

 files  <- c('1A', '.1B' ,.....)
 for (i in 1:length(files)) 
{
 out <-read.csv(paste(dir, "name", files[i], ".txt", sep=''), header=F, 
row.names = NULL, col.names = c("code","value"))
}

To prevent having to reload the ascii files each time, save the object 
called out  

save(out, file = "opc.shuttle.transect1")  

And reload it later

load("opc.shuttle.transect1")  

This works well for me and my files are rather large.

Cheers

Sam



Sam McClatchie, Research scientist (fisheries acoustics))))))))))
NIWA (National Institute of Water & Atmospheric Research Ltd)
PO Box 14 901, Kilbirnie, Wellington, New Zealand
s.mcclatchie at niwa.cri.nz 

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