On Nov 18, 2010, at 10:42 AM, Martin Tomko wrote:
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.
OK. Looking back at your original question it appears you are
confusing the actions of "&" and "|" when setting up selection
criteria. It may sound strange but if you want the union of the group
that is A and the group the is B then the criteria needs to be A | B ,
not A & B.
So your original operation should have been:
subset1<-subset1[ subset1$Class == 1 | subset1$Type == 1 |
subset1$Category == 1, ]
--
David.
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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