Gabor Grothendieck wrote:
2009/10/6 Uwe Ligges <lig...@statistik.tu-dortmund.de>:
The first rule is easy: As long as you are using scalar valued (i.e. length
1 vectors in R) "cond", you should prefer
if(cond) cons.expr else alt.expr
rather than
ifelse(cond, yes, no)
because the latter one evaluates both "yes" and "no" while the former one
evaluates exactly one of both expressions.
I don't think that that is true. The false leg was not evaluated here:
ifelse(TRUE, { cat("a"); 1}, {cat("b"); 2})
a[1] 1
Ah, indeed that changed at some point and I forgot that the code checks
for the length of cond nowadays. Thanks for pointing it out.
Best wishes,
uwe
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