[R] argh .. if/else .. why?
ggrothendieck at gmail.com
Mon Feb 15 17:37:32 CET 2010
On Mon, Feb 15, 2010 at 11:24 AM, David Winsemius
<dwinsemius at comcast.net> wrote:
> On Feb 15, 2010, at 11:01 AM, hadley wickham wrote:
>>> I, personally, utilize the ifelse(test,statement,statement) function when
>>> possible over the methodology outlined.
>> if + else and ifelse perform quite different tasks, and in general can
>> not (and should not) be exchanged. In particular, note that for
>> ifelse, "the class attribute of the result is taken from ‘test’ and
>> may be inappropriate for the values selected from ‘yes’ and 'no’".
> I have always been puzzled by that bit of advice/knowledge on the help page.
> "test" will of necessity be of class "logical", and yet I regularly succeed
> in producing numeric and character vectors with ifelse. In fact ifelse would
> be rather limited in utility if it only returned logical vectors.
I think it had intended to refer to oldClass rather than class.
> oldClass(ifelse(TRUE, 1, 2))
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