[R] ifelse()

[jim holtman]

Take it in a couple of steps.  'ifelse' will take the evaluation of a
logical vector (first parameter) and return it second parameter if
TRUE or the third parameter if FALSE:

> X<-c(2,2,1,1,0,0)
> X > 0
[1]  TRUE  TRUE  TRUE  TRUE FALSE FALSE
> ifelse(X > 0, 1,0)
[1] 1 1 1 1 0 0
>

Now the second and third parameters can also be vectors and the
corresponding value will be chosen:

> ifelse(X > 0, 1:6, 11:16)
[1]  1  2  3  4 15 16
>

HTH

On Tue, Feb 10, 2009 at 4:44 PM, kayj <kjaja27 at yahoo.com> wrote:
>
> I have a problem with ifelse(), I do not understand how it works.
>
>> X<-c(2,2,1,1,0,0)
>> str(X)
>  num [1:6] 2 2 1 1 0 0
>> Y<-ifelse(X>0,1,0)
>> Y
> [1] 1 1 1 1 0 0
>>
>
> Can some one explain what is going on, I do not understand what ifelse is
> doing in this case. Can someone explain the output Y.
>
> Thanks
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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