Re: subset

Mon, 19 Jan 1998 10:25:38 -0600 (CST)

Regarding my suggestion that the function subset.df() published previously
on the s-news mailing list might better be named and
operate as a method for a generic function subset(), Jens Oehlschlaegel
pointed out that a function subset() already is in use after having been
contributed to the s-news earlier. I then suggested that the existing
subset() might be dispensible. Jens responded,

>>I would like to keep the old subset() for efficiency, look at the

> dim(basic)
[1] 1247 247
> dos.time(names(subset(basic,PAT==100)))
[1] 2.420006
> dos.time(names(df.subset(basic,PAT==100)))
[1] 19.06

Factor 8 is quite a differ

Also it can be an advantage, if factors are *not* automatically changed,
e.g. if you want to
tabulate empty categories also, or to get a warning on
empty categories rather than smoothly running an analysis you don't
really want.

Jens, you have convinced me.


John Thaden
University of ARkansas for Medical Sciences
Little Rock Arkansas USA