  Hi!

I don't really understand your goal, but if you want to extract the row 
names,
rownames(a[which(a[,3] < 8), ])
does it.

But I think you've already tried it. Maybe it's just me...

HTH
Ivan

Le 9/3/2010 15:08, syrvn a écrit :
> Hi,
>
> the R code:
>
> a<- matrix(c(1,5,4,3,7,10,34,4,3,8,6,5,12,17,45,3,2,45,46,47,3,4,22,12,21),
> nrow=5)
> rownames(a)<- c("a","b","c","d","e")
> a
> a[which(a[,3]<  8), ]
> a[which(a[,3]<  6), ]
>
>
> produces the following output:
>
>> a
>    [,1] [,2] [,3] [,4] [,5]
> a    1   10    6    3    3
> b    5   34    5    2    4
> c    4    4   12   45   22
> d    3    3   17   46   12
> e    7    8   45   47   21
>
>> a[which(a[,3]<  8), ]
>    [,1] [,2] [,3] [,4] [,5]
> a    1   10    6    3    3
> b    5   34    5    2    4
>
>> a[which(a[,3]<  6), ]
> [1]  5 34  5  2  4
>
>
> I actually thought it must be rather easy to somehow extract the row name
> when the result is just a vector as in the second example and not a matrix.
> I tried several ways but without any success.
>
> Any advice?
> Best,
> syrvn
>
>

-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra@uni-hamburg.de

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