[R] problems subsetting
dwinsemius at comcast.net
Thu Nov 18 16:53:01 CET 2010
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, ]
> Any idea?
> On 11/18/2010 4:35 PM, Steve Lianoglou wrote:
>> On Thu, Nov 18, 2010 at 10:25 AM, Martin Tomko<martin.tomko at geo.uzh.ch
>> > wrote:
>>> Hi Gerrit,
>>> indeed, that works. Excellent tip!
>>> For reference, I did this:
>>> 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)
>>  FALSE TRUE FALSE TRUE
>> R> c(TRUE, TRUE, FALSE, TRUE)&& c(FALSE, TRUE, TRUE, TRUE)
>>  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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David Winsemius, MD
West Hartford, CT
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