This should do what you want: (it uses loops; you can work at
replacing those with 'lapply' and such -- it all depends on if it is
going to take you more time to rewrite the code than to process a set
of data; you never did say how large the data was). This also "grows"
a data.frame, but you have not indicated how efficient is has to be.
So this could be used as a model.
> x <- readLines(textConnection("x x_string
+ y y_string
+ id1 id1_string
+ id2 id2_string
+ z z_string
+ w w_string
+ stuff stuff stuff
+ stuff stuff stuff
+ stuff stuff stuff
+ //
+ x x_string1
+ y y_string1
+ z z_string1
+ w w_string1
+ stuff stuff stuff
+ stuff stuff stuff
+ stuff stuff stuff
+ //
+ x x_string2
+ y y_string2
+ id1 id1_string1
+ id2 id2_string1
+ z z_string2
+ w w_string2
+ stuff stuff stuff
+ stuff stuff stuff
+ stuff stuff stuff
+ //"))
> # I assume that each group is delimited by "//"
> # initialize data.frame with desired values
> .keys <- data.frame(x=NA, y=NA, id1=NA, id2=NA, w=NA)
> .out <- .keys # for the first pass
> .save <- NULL
> for (i in seq_along(x)){
+ if (x[i] == "//"){ # output the current data
+ .save <- rbind(.save, .out)
+ .out <- .keys # setup for the next pass
+ } else {
+ .split <- strsplit(x[i], "\\s+")
+ if (.split[[1]][1] %in% names(.out)){
+ .out[[.split[[1]][1]]] <- .split[[1]][2]
+ }
+ }
+ }
> .save
x y id1 id2 w
1 x_string y_string id1_string id2_string w_string
2 x_string1 y_string1 <NA> <NA> w_string1
3 x_string2 y_string2 id1_string1 id2_string1 w_string2
On Wed, Jul 9, 2008 at 5:33 AM, Paolo Sonego <[EMAIL PROTECTED]> wrote:
> Dear R users,
>
> I have a big text file formatted like this:
>
> x x_string
> y y_string
> id1 id1_string
> id2 id2_string
> z z_string
> w w_string
> stuff stuff stuff
> stuff stuff stuff
> stuff stuff stuff
> //
> x x_string1
> y y_string1
> z z_string1
> w w_string1
> stuff stuff stuff
> stuff stuff stuff
> stuff stuff stuff
> //
> x x_string2
> y y_string2
> id1 id1_string1
> id2 id2_string1
> z z_string2
> w w_string2
> stuff stuff stuff
> stuff stuff stuff
> stuff stuff stuff
> //
> ...
> ...
>
>
> I'd like to parse this file and retrieve the x, y, id1, id2, z, w fields and
> save them into a a matrix object:
>
> x y id1 id2 z w
> x_string y_string id1_string id2_string z_string w_string x_string1
> y_string1 NA NA z_string1 w_string1
> x_string2 y_string2 id1_string1 id2_string1 z_string2 w_string2
> ...
> ...
>
> id1, id2 fields are not always present within a section (the interval
> between x and the last stuff) and
> I'd like to insert a NA when they are absent (see above) so that
> length(x)==length(y)==length(id1)==... .
>
> Without the id1, id2 fields the task is easily solvable importing the text
> file with readLines and retrieving the single fields with grep:
>
> input = readLines("file.txt")
> x = grep("^x\\s", input, value = T)
> id1 = grep("^id1\\s", input, value = T)
> ...
>
> I'd like to accomplish this task entirely in R (no SQL, no perl script),
> possibly without using loops.
>
> Any suggestions are quite welcome!
>
> Regards,
> Paolo
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
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