David Winsemius
On Jan 30, 2009, at 7:46 AM, Jonathan Dushoff wrote:
> I have a list of observations of individuals. I would like to make
> a list of individuals, with a data frame of observations for each
> individual.
>
> The following code usually works, but not always
>
> ----------------------------------------------------------------------
>
> # Make a list of empty data frames
> animals = list()
> indivs = levels(Z$individual_id)
> donotprint <- sapply(indivs, function(i){
> animals[[i]] = data.frame()
> })
>
> # Add observations of each animal to the appropriate frame
> donotprint <- apply(Z, 1, function(r){
> ind = r[["individual_id"]]
> bind = ind # Use different names to confirm that the partial
> matching is being done on the left
>
> animals[[bind]]$sighting_number <<-
> c(animals[[ind, exact=TRUE]]$sighting_number,
> r[["sighting_number"]])
> animals[[bind]]$date<<-
> c(animals[[ind, exact=TRUE]]$date, r[["date"]])
> animals[[bind]]$age <<-
> c(animals[[ind, exact=TRUE]]$age, r[["age_num"]])
> })
>
> ----------------------------------------------------------------------
>
> The problem is partial matching. When it gives the wrong answer, it
> gives partial match warnings. Adding "exact=TRUE" to the left, the
> way that I added it to the right, simply produces an argument
> error. Changing to single brackets produces other errors.
>
> I read the help, and the Language Definition (not the whole thing),
> but could not find clear documentation of what single brackets with
> character variable arguments are supposed to do in lists, nor of how
> partial matching is handled on the left side of an assignment, nor
> of whether R is supposed to do partial-match indexing when an exact
> match is available (I would have thought not, and it's documented
> that it's not supposed to for function arguments).
>
> I am interested in how the subsetting is supposed to work, but even
> more in what might be the best way to code this sort of thing in R.
>
> I am using R 2.6.2 on Mandriva linux.
>
> Thanks for any help,
>
> JD
>
> ______________________________________________
> R-help at 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.