[R] when to use `which'?

[Bert Gunter]

Well ...
which(a==4)^2

??

-- Bert

On Tue, Jul 12, 2011 at 1:17 PM, Sam Steingold <sds at gnu.org> wrote:
> when do I need to use which()?
>> a <- c(1,2,3,4,5,6)
>> a
> [1] 1 2 3 4 5 6
>> a[a==4]
> [1] 4
>> a[which(a==4)]
> [1] 4
>> which(a==4)
> [1] 4
>> a[which(a>2)]
> [1] 3 4 5 6
>> a[a>2]
> [1] 3 4 5 6
>>
>
> seems unnecessary...
>
> --
> Sam Steingold (http://sds.podval.org/) on CentOS release 5.6 (Final) X 11.0.60900031
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>
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-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
possible to reach the ultimate truths without the elementary studies
usually prefixed to them, these would not be preparatory studies but
superfluous diversions."

-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics