R help - Jul 2013 - list construction with automatic names

I often find myself (wanting t)o constructing lists or data.frames like so:

#Find files in subdirs
ii <- 0
for (ix in id) {
	ii <- ii + 1
	if (ii == 1) {
		fl <- list(basename(ix) = list.files(ix))
	} else {
		fl <- c(fl, list(basename(ix) = list.files(ix)))
	}
}

The above is for list construction. It does not work as the argument name
is not accepted. In python this would be legal but I can't find how to
modify the name argument in R to make this legal.

Furthermore the use of a separate counter is not very elegant. Would there
be a better way? Again, in python appending to a list is very easy but
seems to be available in R only for vectors not lists?

Any help much appreciated!
Alex van der Spek

> I often find myself (wanting t)o constructing lists or 
> data.frames:
Try something like

fl<-list()
for (ix in id) {
	fl[[basename(ix)]] <- list.files(ix)
}
But read R Inferno on inrementing objects first. It isn't efficient in
memory terms (unless that's improved in recent versions of R)
 
Rather more elegantly you can get the same list with

sapply(id, function(ix) list.files(ix))



*******************************************************************
This email and any attachments are confidential. Any use...{{dropped:8}}

> I often find myself (wanting t)o constructing lists or 
> data.frames
 
Apologies; previous post should have said "Read R inforno on 'Growing
Objects'" and should have added the URL:

http://www.burns-stat.com/pages/Tutor/R_inferno.pdf

S Ellison



*******************************************************************
This email and any attachments are confidential. Any use...{{dropped:8}}