[R] unique deletes names - intended?

[Heinz Tuechler]

Thank you for your clarification.

At 11:04 05.07.2006 +0100, Prof Brian Ripley wrote:
>On Tue, 4 Jul 2006, Heinz Tuechler wrote:
>
>> Dear All,
>>
>> as shown in the example, unique() deletes names of vector elements.
>> Is this intended?
>
>Yes.  Think of the vector as a set: it is supposed to immaterial which of 
>the duplicated elements is retained.
>
>The help page says
>
>      An object of the same type of 'x'. but if an element is equal to
>      one with a smaller index, it is removed.
>
>so it is starting with a new object, not 'x'.  However, the array method 
>works differently, so the documentation needs clarification.
>
>> Of course, one can use indexing by !duplicated() instead.
>
>Be careful, as you might get a method for [ and that might not do want you 
>intended (e.g. for a time series).
>
>
>> Greetings,
>> Heinz
>>
>> ## unique deletes names
>> v1 <- c(a=1, b=2, c=3, e=2, a=4)
>> unique(v1) # names deleted
>>
>> v1[!duplicated(v1)] # names preserved
>>
>>
>> platform       i386-pc-mingw32
>> arch           i386
>> os             mingw32
>> system         i386, mingw32
>> status         Patched
>> major          2
>> minor          3.1
>> year           2006
>> month          07
>> day            01
>> svn rev        38471
>> language       R
>> version.string Version 2.3.1 Patched (2006-07-01 r38471)
>>
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>>
>
>-- 
>Brian D. Ripley,                  ripley at stats.ox.ac.uk
>Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>University of Oxford,             Tel:  +44 1865 272861 (self)
>1 South Parks Road,                     +44 1865 272866 (PA)
>Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>
>