[R] FW: Sum by categorical variable

Petr Pikal petr.pikal at precheza.cz
Wed May 7 11:43:44 CEST 2003


Hi

On 6 May 2003 at 16:53, De Amicis Fabrizio (G.I.T.) wrote:

> 
> Another easy(/stupid) question:
> 
> with the following command
>  j2<-xf1[1:10,"V4"]
> I have 
> 
> > j2
>  [1] CHROMOLI             LINEAGERMAI          RINALDI             
>  GIUNTIMA
> AUTOSTELLA          
>  [6] CAIZZONE             CENTRO B PEL E C SNC CONSORZI            
>  MAN NORD
> PDM                 
> 1304 Levels:   MACHIAVELLI Snc  MENARINI MANUFACTURERS LOGISTICS
> SERVICES ... ZUCCHERIFICIO DEL MOLISE
> 
> 
> Why j2 has 1304 Levels (I know that xf has 1304 rows)? How can I
> obtain a vector of 10 elements?
You actually have got first 10 elements of variable "V4" in j2 

see length(j2), 

but as it is a factor the level attribute has retained an information 
about all different levels of "V4" which I presume is 1304. To get 
rid of these levels just use

factor(j2)


> 
> Thank you 
> 
> 
> >  
> > 
> > ---------------------------------------------------------------
> > Fabrizio De Amicis
> > 
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> > 
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CheersPetr Pikal
petr.pikal at precheza.cz
p.pik at volny.cz




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