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

Wed Apr 7 13:56:03 CEST 2010

> This is rather by chance due to numeric instabilities, I think:
It looks like something else is going on in addition to potential problem
with numerical instabilities:

p <- runif(length(letters))
q <- gset(letters, p)
all.equal(p,p)
all.equal(q,q)
q == q

> p <- runif(length(letters))
> q <- gset(letters, p)
> all.equal(p,p)
[1] TRUE
> all.equal(q,q)
[1] "target and current have different memberships"
> q == q
[1] FALSE
>

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-----Original Message-----
From: David Meyer [mailto:david.meyer at wu.ac.at] 
Sent: Tuesday, April 06, 2010 6:03 PM
To: Czerminski, Ryszard
Cc: Peter Ehlers; R-help at R-project.org; David Meyer
Subject: Re: [R] library sets: A & EMPTY does not work; gset_intersection(A,EMPTY) works

This is rather by chance due to numeric instabilities, I think:

 > uv <- c('a', 'b', 'c'); s <- gset(uv, runif(length(uv)))
 > s
{"a" [0.7533966], "b" [0.968067], "c" [0.2494876]}
 > s == s
[1] TRUE
 > gset_is_equal(s,s)
[1] TRUE

But using all.equal instead of `==` for the memberships might by a good 
idea, I will have a look at it.

Thanks
David

Czerminski, Ryszard wrote:
> Hi Peter,
> 
> This looks like another one: "gset_is_equal(X,X)" and "X == X" evaluate to FALSE ?
> 
>> uv <- c('a', 'b', 'c'); s <- gset(uv, runif(length(uv)))
>> s
> {"a" [0.0811552], "b" [0.3552998], "c" [0.996772]}
>> gset_is_equal(s, s)
> [1] FALSE
>> s == s
> [1] FALSE
>> class(s)
> [1] "gset" "cset"
> 
> Best regards,
> Ryszard
> 
> 
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>  
> -----Original Message-----
> From: Peter Ehlers [mailto:ehlers at ucalgary.ca] 
> Sent: Wednesday, March 31, 2010 2:03 PM
> To: Czerminski, Ryszard
> Cc: R-help at r-project.org; David Meyer
> Subject: Re: [R] library sets: A & EMPTY does not work; gset_intersection(A,EMPTY) works
> 
> Ryszard,
> 
> You've made me take a closer look and now I do think that
> you've found a bug.
> 
> After a quick look at the package vignette, I see that the
> authors have indeed overloaded "&" and so it should work for
> your example. The problem seems to be the order of the class
> attribute which is used to call the relevant 'Ops' function:
> 
> class(A)
> #[1] "gset" "cset"
> 
> class(B)
> #[1] "gset" "cset"
> 
> class(E <- A - A)
> #[1] "set"  "gset" "cset"
> 
> If you re-order the class vector, function Ops.gset will be called
> to handle A and E:
> 
> class(E) <- class(E)[c(2,3,1)]
> A & E
> #{}
> 
> I've cc'd David Meyer.
> 
>   -Peter Ehlers
> 
> On 2010-03-31 10:11, Czerminski, Ryszard wrote:
>> It seems that "A&  B" works the same way as "gset_intersection(A,B)"
>> as long as A and B are not empty...
>> see below:
>>
>> fuzzy_logic("Yager", p=2)
>> support<- universe<- c('a','b','c','d')
>> A<- gset(support=support, memberships=c(0.2, 0.2, 0.9, 0),
>> universe=universe)
>> B<- gset(support=support, memberships=c(0.211, 0.222, 0.999, 0),
>> universe=universe)
>> A
>> B
>> A&  B
>> gset_intersection(A,B)
>> E<- A - A
>> A&  E
>> gset_intersection(A,E)
>>
>>> fuzzy_logic("Yager", p=2)
>>> support<- universe<- c('a','b','c','d')
>>> A<- gset(support=support, memberships=c(0.2, 0.2, 0.9, 0),
>> universe=universe)
>>> B<- gset(support=support, memberships=c(0.211, 0.222, 0.999, 0),
>> universe=universe)
>>> A
>> {"a" [0.2], "b" [0.2], "c" [0.9]}
>>> B
>> {"a" [0.211], "b" [0.222], "c" [0.999]}
>>> A&  B
>> {"c" [0.899995]}
>>> gset_intersection(A,B)
>> {"c" [0.899995]}
>>> E<- A - A
>>> A&  E
>> Error in A&  E :
>>    operations are possible only for numeric or logical types
>> In addition: Warning message:
>> Incompatible methods ("Ops.gset", "Ops.set") for "&"
>>> gset_intersection(A,E)
>> {}
>>
>>
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>>
>> -----Original Message-----
>> From: Peter Ehlers [mailto:ehlers at ucalgary.ca]
>> Sent: Wednesday, March 31, 2010 11:43 AM
>> To: Czerminski, Ryszard
>> Cc: R-help at r-project.org
>> Subject: Re: [R] library sets: A&  EMPTY does not work;
>> gset_intersection(A,EMPTY) works
>>
>> 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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> 

-- 
Priv.-Doz. Dr. David Meyer
Department of Information Systems and Operations

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