> Just stating, in 'ifelse', 'test' is not recycled. As I said in "R-intro:
> length of 'ifelse' result"
> (https://stat.ethz.ch/pipermail/r-devel/2016-September/073136.html),
> ifelse(condition, a, b)
> returns a vector of the length of 'condition', even if 'a' or 'b' is longer.
That is indeed (almost) the documented behaviour. The documented behaviour is
slightly more complex; '... returns a value _of the same shape_ as 'test''. IN
principle, test can be a matrix, for example.
> A concrete version of 'ifelse2' that starts the result from 'yes':
> .. still a bit disappointed that nobody has taken a look ...
I took a look. The idea leaves (at least) me very uneasy. If you are recycling
'test' as well as arbitrary-length yes and no, results will become
frighteningly hard to predict except in very simple cases where you have
well-defined and consistent regularities in the data. And where you do, surely
passing ifelse a vetor of the right length, generated by rep() applied to a
short 'test' vector, will do what you want without messing around with new
functions that hide what you're doing.
Do you really have a case where 'test' is neither a single logical (that could
be used with 'if') nor a vector that can be readily replicated to the desired
length with 'rep'?
If not, I'd drop the attempt to generate new ifelse-like functions.
S Ellison
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