[R-sig-eco] Selecting levels from a list

[Owen Jones]

Try the %in% notation which works like this:

> x<-as.factor(LETTERS[1:10])
> x
 [1] A B C D E F G H I J
Levels: A B C D E F G H I J
> x[x%in%c("C","J")]
[1] C J
Levels: A B C D E F G H I J


Cheers,
Owen


On Wed, Dec 3, 2008 at 4:46 PM, <Jeffrey_Warren at fws.gov> wrote:

>
> I'm trying to select multiple levels from a list of factors but have not
> been able to.  Here is the list:
>
>  lesc.ddl$p$time
>  [1] 0.75  0.833 1     1.75  1.833 2     2.75  2.833 3     3.75  3.833 4
> 0.833 1     1.75  1.833 2     2.75  2.833 3     3.75  3.833 4     1
> 1.75
> [26] 1.833 2     2.75  2.833 3     3.75  3.833 4     1.75  1.833 2     2.75
> 2.833 3     3.75  3.833 4     1.833 2     2.75  2.833 3     3.75  3.833 4
> [51] 2     2.75  2.833 3     3.75  3.833 4     2.75  2.833 3     3.75
> 3.833 4     2.833 3     3.75  3.833 4     3     3.75  3.833 4     3.75
> 3.833 4
> [76] 3.833 4     4
> Levels: 0.75 0.833 1 1.75 1.833 2 2.75 2.833 3 3.75 3.833 4
>
> And the code I've tried so far:
>
> lesc.ddl$p$time==0.75 | 1.75 | 2.75  #returns all 'TRUE' values
>
> lesc.ddl$p$time==c(0.75 | 1.75 | 2.75)  #returns all 'FALSE' values
>
> Any help would be greatly appreciated.
>
> Cheers,
>
> Jeff Warren
> Wildlife Biologist
> Red Rock Lakes NWR
> Lima, Montana 59739
> (406) 276-3536
>
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>



-- 
Dr Owen Jones
Imperial College London,
Silwood Park Campus,
Ascot.
SL5 7PY
UK

Tel: +44(0)20 75942489
Email: owen.jones at imperial.ac.uk
Website:http://www3.imperial.ac.uk/people/owen.jones