[R] library sets: A & EMPTY does not work; gset_intersection(A,EMPTY) works

[Peter Ehlers]

On 2010-03-31 9:30, Peter Ehlers wrote:
> Unless I'm missing something, I don't see any method
> in pkg:sets for intersection other than gset_intersection.

Whoops, a bit quick on the draw.
There are of course also set_intersection and cset_intersection,
but not AFAICS any method for `&`.

  -Peter Ehlers

> So you're using the base R function `&` whose help page
> tells you that its arguments should be vectors. Yours
> aren't.
>
> -Peter Ehlers
>
> On 2010-03-31 8:50, Czerminski, Ryszard wrote:
>> When using generalized sets from "sets" library
>>
>> A& EMPTY does not work, but gset_intersection(A,EMPTY) works: example
>> code below
>>
>> Is it a bug?
>>
>> Best regards,
>> Ryszard
>>
>> library(sets)
>> support<- universe<- c('a','b','c','d')
>> A<- gset(support=support, memberships=c(0.2, 0.2, 0.9, 0),
>> universe=universe)
>> class(A)
>> A
>> E<- A - A # create empty set
>> I<- gset_intersection(A, E) #<<< this WORKS
>> class(I); I
>> I<- A& E #<<< this DOES NOT WORK
>>
>> # ---
>>
>>> support<- universe<- c('a','b','c','d')
>>> A<- gset(support=support, memberships=c(0.2, 0.2, 0.9, 0),
>> universe=universe)
>>> class(A)
>> [1] "gset" "cset"
>>> A
>> {"a" [0.2], "b" [0.2], "c" [0.9]}
>>> E<- A - A
>>> I<- gset_intersection(A, E) #<<< this WORKS
>>> class(I); I
>> [1] "set" "gset" "cset"
>> {}
>>> I<- A& E #<<< this DOES NOT WORK
>> Error in A& E :
>> operations are possible only for numeric or logical types
>> In addition: Warning message:
>> Incompatible methods ("Ops.gset", "Ops.set") for "&"
>>
>>
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>>
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>

-- 
Peter Ehlers
University of Calgary