>>>>> "Gabor" == Gabor Grothendieck <[EMAIL PROTECTED]>
>>>>> on Sun, 21 May 2006 09:47:07 -0400 writes:
Gabor> If you know that test is a scalar
Gabor> result <- if (test) a else b
Gabor> will do it.
Yes, indeed!
IMO, ifelse(test, a, b) is much overused where as
if(test) a else b is much UNDER used.
>From some e-mail postings, and even some documents (even printed
books?), I get the impression that too many people think that
ifelse(.,.,.) is to be used as expression / function and
if(.) . else . only for "program flow control".
This leads to quite suboptimal code, and I personally use
if(.) . else . __as expression__ much more frequently than ifelse(.,.,.)
Martin Maechler, ETH Zurich.
Gabor> Here is another approach:
Gabor> as.vector(test * ts(a) + (!test) * ts(b))
Gabor> On 5/21/06, ivo welch <[EMAIL PROTECTED]> wrote:
>> Dear R wizards:
>>
>> I just got stung by the ifelse() feature.
>>
>> > a <- 10:15
>> > b <- 20:300
>> > test <- 1
>> > ifelse(test,a,b)
>> [1] 10
>>
>> I had not realized that this was the default behavior---I had expected
>> 10:15. mea culpa. however, I wonder whether it would make sense to
>> replace ifelse with a different semantic, where if test is a single
>> scalar, it means what a stupid user like me would imagine.
>>
>> Aside, I like the flexibility of R, but I am not thrilled by all the
>> recycling rules. I either mean I want a scalar or a vector of
>> equal/appropriate dimension. I never want a recycle of a smaller
>> vector. (I do often use a recycle of a scalar.)
>>
>> regards,
>>
>> /iaw
>>
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Gabor> ______________________________________________
Gabor> [email protected] mailing list
Gabor> https://stat.ethz.ch/mailman/listinfo/r-help
Gabor> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
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