I have not seen you describe the value of doing partial matching in
this application, so pardon this perhaps non-responsive reply:
Wouldn't it have been much, much simpler to have used the subset
function (which returns a dataframe object) at the first assignment to
donotprint?
Something along the lines of (untested) :
donotprint <- sapply(indivs, function(i){
animals[[i]] = subset(Z, individual_id == i, select =
c(sighting_number, date, age_num) ) } # reconsider naming variable
"date"
)
--
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
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and provide commented, minimal, self-contained, reproducible code.
