[R] R design (was "Variable passed to function not used in function in select)

Peter Dalgaard p.dalgaard at biostat.ku.dk
Tue Nov 11 23:29:31 CET 2008

Ben Bolker wrote:

>   Sometime soon when I have the time and energy I will start
> campaigning for an additional "drop" argument to subset that
> does what one expects (!!??) with subsetted factor variables ...

Not that one again! For at least one other value of one, the expectation 
is the opposite: Factor levels do not go away just because they happen 
not to be present in data.

fct <- lapply(dd, is.factor)
dd[fct] <- lapply(dd[fct], "[", drop=TRUE)

and begone with it...

    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

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