"an assignment to a square bracket" implies that the object
already exists and gives an error if it does not. Consider the following:
> a[] <- 1:3
Error: Object "a" not found
> a <- 1:2
> a[] <- 1:3
Warning message:
number of items to replace is not a multiple of replacement length
>
hope this helps. spencer graves
[EMAIL PROTECTED] wrote:
thank you
sorry, but i missed that thread
your solution works (of cause)
hopefully the code and not the documentation will be corrected as the drop
argument comes very convenient or maybe as a new option: drop.unused.levels=T
regards soren
btw
how do i interpret an assigment to a square bracket?
d2[] <- lapply(d2, function(x) if (is.factor(x)) factor(x) else x)
----- Original Message -----
From: "Peter Dalgaard" <[EMAIL PROTECTED]>
To: "Søren Merser" <[EMAIL PROTECTED]>
Cc: "R - help" <[EMAIL PROTECTED]>
Sent: Sunday, June 27, 2004 11:38 AM
Subject: Re: [R] subset drop unused levels
Søren Merser <[EMAIL PROTECTED]> writes:
hi there
tried to use subset with drop=TRUE, but all the 'old' levels are preserved,
i.e. when calling e.g. ftable a lot of zeros are displayed
x<-subset(LREG, (kir=='AA' | kir=='BB') & (type=='t1' | otype=='t2'),
drop=TRUE, select=c(event, kir, type))
ftable(x)
i explicit have to call factor like
ftable(event~factor(kir)+factor(type))
any hints?
Yes, the drop argument is misdocumented. It actually does the same as
the drop argument to [.data.frame. It was on this very list just
eleven days ago, see e.g. the below ref., including what to do if you
really want to get rid of unused levels
http://www.mail-archive.com/[EMAIL PROTECTED]/msg22459.html
(yet another interface to the archives...)
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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