Here is an example:
# read and print first 10 lines one by one
# the next two lines could be collapsed into con <- file("myfile", r)
con <- file("myfile")
open(con)
for(i in 1:10) print(readLines(con, n=1))
close(con)
Also its possible that you may not need open. For example,
one can just read it all in at once like this:
mylines <- readLines("myfile")
# and now mylines[1] is the first line, etc.
# or
my.numbers <- scan("myfile")
# or
my.table <- read.table("myfile")
On 4/14/05, Na Li <[EMAIL PROTECTED]> wrote:
>
> I'm been doing more and more of file text parsing inside R instead of
> coping with Perl. For that, I need open a file and read it line-by-line.
> I found the documentation for 'open' isn't very clear.
>
> Right now it has
>
> ,----[ *help(R)[open]* ]
> | 'open' opens a connection. In general functions using connections
> | will open them if they are not open, but then close them again, so
> | to leave a connection open call 'open' explicitly.
> `----
>
> It seems that one has to call 'open' to open a live connection that can be
> parsed line by line (using readLines() or scan() to read). But open()
> cannot be directly applied to a file name.
>
> In fact, one only needs supply the 'open' argument in file() with
> something other than the empty string,
>
> ,----
> | > con <- file ("S200.dat")
> | > isOpen (con)
> | [1] FALSE
> | > con <- file ("S200.dat", open = "r")
> | > isOpen (con)
> | [1] TRUE
> `----
>
> It is not clear to me how 'open()' is supposed to be used. It took me a
> while to figure this out and I thought it might be worthwhile to add one
> sentence or two to make it more clear in the doc.
>
> Cheers,
>
> Michael
>
> --
> Na (Michael) Li, Ph.D.
> Division of Biostatistics A443 Mayo Building, MMC 303
> School of Public Health 420 Delaware St SE
> University of Minnesota Minneapolis, MN 55455
> Phone: (612) 626-4765 Email: [EMAIL PROTECTED]
> Fax: (612) 626-0660 http://www.biostat.umn.edu/~nali
>
> GPG Public Key:
> http://www.umn.edu/lookup?SET_INSTITUTION=UMNTC&UID=nali&show_pgp=1
>
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