Thanks Steve, that explains it... Unfortunately, I did nto get that from my R docs...

I am still searching for a solution for matching the entries in my matrix by matching the rownames to the entires in a subset I got using Gerrit's method.

Any idea?
Thanks
Martin

On 11/18/2010 4:35 PM, Steve Lianoglou wrote:
Hi,

On Thu, Nov 18, 2010 at 10:25 AM, Martin Tomko<martin.to...@geo.uzh.ch>  wrote:
Hi Gerrit,
indeed, that works. Excellent tip!

For reference, I did this:

subset1<-subset(summarystats,(Type==1)&(Class==1)&(Category==1))

I am still not totally sure when one uses "&" amd when"&&"  - I was under
the impression that&&  stands for logical AND....
If you can't find the appropriate documentation, try to experiment in
your workspace:

R>  c(TRUE, TRUE, FALSE, TRUE)&  c(FALSE, TRUE, TRUE, TRUE)
[1] FALSE  TRUE FALSE  TRUE

R>  c(TRUE, TRUE, FALSE, TRUE)&&  c(FALSE, TRUE, TRUE, TRUE)
[1] FALSE

The single logical operators (&  , |) run over the entire length of
your logical vectors.
The doubles (&&, ||) just evaluate the first element of the vectors,
and ignore the rest.



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