R help - Dec 2010 - Faster way to do it??...using apply?

Hi, 
I have a simple task, but I am looking for a clever and fast way to do it:

I have a vector x with 0,1 or 2 and I want to create another vector y with
the same length following the rules:
If the element in x is equal to 0, the element in y is equal to 0
If the element in x is equal to 2, the element in y is equal to 1
If the element in x is equal to 1, the element in y is either 0 or 1 (sample
from c(0,1))

thus the vector
> x
     [,1]
[1,]    0
[2,]    2
[3,]    1
[4,]    2
[5,]    0
[6,]    1
[7,]    2

could produce the vector y (this is one of the possibilities since y|x=1 is
either 0 or 1
> y
     [,1]
[1,]    0
[2,]    1
[3,]    1
[4,]    1
[5,]    0
[6,]    0
[7,]    1


I know how to do this using for loops but I was wondering if you guys could
suggest a better way
Thanks

-- 
View this message in context:
http://r.789695.n4.nabble.com/Faster-way-to-do-it-using-apply-tp3166161p3166161.html
Sent from the R help mailing list archive at Nabble.com.

Try this:

replace(replace(x, x == 1, sample(0:1, 1)), x == 2, 1)

On Tue, Dec 28, 2010 at 2:43 PM, M.Ribeiro <mresendeufv@yahoo.com.br>
wrote:
>
> Hi,
> I have a simple task, but I am looking for a clever and fast way to do it:
>
> I have a vector x with 0,1 or 2 and I want to create another vector y with
> the same length following the rules:
> If the element in x is equal to 0, the element in y is equal to 0
> If the element in x is equal to 2, the element in y is equal to 1
> If the element in x is equal to 1, the element in y is either 0 or 1
> (sample
> from c(0,1))
>
> thus the vector
> > x
>     [,1]
> [1,]    0
> [2,]    2
> [3,]    1
> [4,]    2
> [5,]    0
> [6,]    1
> [7,]    2
>
> could produce the vector y (this is one of the possibilities since y|x=1 is
> either 0 or 1
>
> > y
>     [,1]
> [1,]    0
> [2,]    1
> [3,]    1
> [4,]    1
> [5,]    0
> [6,]    0
> [7,]    1
>
>
> I know how to do this using for loops but I was wondering if you guys could
> suggest a better way
> Thanks
>
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/Faster-way-to-do-it-using-apply-tp3166161p3166161.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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