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

[Peter Ehlers]

Unless I'm missing something, I don't see any method
in pkg:sets for intersection other than gset_intersection.
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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-- 
Peter Ehlers
University of Calgary