[R] extracting names from matrix according to a condition

[Peter Ehlers]

On 2011-04-25 10:58, ivan wrote:
> Dear Community,
>
> I have a matrix with assigned colnames and rolnames as follows:
>
>              A            B
> NR    0.15      0,05
> AL     0,05      0,05
> .           .            .
> .           .            .
> .           .            .
>
> I want to extract the names of the rows for which A>0,1 and B<0,1. In
> the above example this would be observation NR only. Hence the output
> should write for instance:
>
> names:
> NR
>
> Is this possible? Thank you very much for your help.

Call the matrix m. Then

  rownames(m[ m[, "A"] > 0.1 & m[, "B"] < 0.1, , drop=FALSE ])

should do what you want.

Peter Ehlers