[Rd] inaccuracy in man page for duplicated() + anyDuplicated() not working with MARGIN=0

[Hervé Pagès]

Sounds good. Thanks Martin!  H.

On 11-11-17 03:20 AM, Martin Maechler wrote:
>
>> Hi,
>> In man page for duplicated:
>
>>     Value:
>
>>        ‘duplicated()’: For a vector input, a logical vector of the same
>>        length as ‘x’.  For a data frame, a logical vector with one
>>        element for each row.  For a matrix or array, a logical array with
>>        the same dimensions and dimnames.
>
>> When 'x' is a matrix or array, the returned value is NOT a logical
>> array:
>
>>     >  m<- matrix(c(3,2,7,6,2,7), nrow=3)
>>     >  m
>>          [,1] [,2]
>>     [1,]    3    6
>>     [2,]    2    2
>>     [3,]    7    7
>>     >  duplicated(m)
>>     [1] FALSE FALSE FALSE
>
>> Only if MARGIN=0 it seems:
>
>>     >  duplicated(m, MARGIN=0)
>>           [,1]  [,2]
>>     [1,] FALSE FALSE
>>     [2,] FALSE  TRUE
>>     [3,] FALSE  TRUE
>
> Indeed. Thank you for pointing this out.
> I'll definitely fix that part of the help file.
>
>> Also, any reason why this doesn't work?
>
>>     >  anyDuplicated(m, MARGIN=0)
>>     Error in dim(newX)<- c(prod(d.call), d2) :
>>       dims [product 1] do not match the length of object [6]
>
> well, because the R core colleague enhanced duplicated.array()
> to work with MARGIN 0 (and similar cases) did not
> update the parallel code in anyDuplicated.array() correspondingly.
>
>> May be it could be equivalent to:
>
>>     >  anyDuplicated(as.vector(m))
>>     [1] 5
>
> Yes, that's what will happen after I've committed my fixes.
>
> Thank you very much, Hervé!
> Martin
>
> [...]
>
>> --
>> Hervé Pagès
> [...]
>
> (*) having authored anyDuplicated()
>


-- 
Hervé Pagès

Program in Computational Biology
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