[R] ifelse(logical, function1, function2) does not work

[Peter Dalgaard]

Alberto Vieira Ferreira Monteiro <albmont at centroin.com.br> writes:

> Why this kind of assignment does not work?
> 
>   n <- 1
>   f <- ifelse(n == 1, sin, cos)
>   f(pi)

It's not supposed to. 

     'ifelse' returns a value with the same shape as 'test' which is
     filled with elements selected from either 'yes' or 'no' depending
     on whether the element of 'test' is 'TRUE' or 'FALSE'.

which makes very little sense if yes and no are functions.
 
> this must be rewritten as:
> 
>   n <- 1
>   f <- cos
>   if (n == 1) f <- sin
>   f(pi)

No, it must not.

n <- 1
f <- if (n==1) sin else cos
f(pi)

or even 

(if (n==1) sin else cos)(pi)

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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