[R] help with this indexing

Adaikalavan Ramasamy ramasamy at cancer.org.uk
Mon May 21 17:11:20 CEST 2007


merge()


javier garcia-pintado wrote:
> Hi all,
> Let's say I have a long data frame and a short one, both with three
> colums: $east, $north, $value
> And I need to fill in the short$value, extracting the corresponding
> value from long$value, for coinciding $east and $north in both tables.
> I know the possibility:
> 
> for (i in 1:length(short$value)){
>  short$value[i] <- long$value[long$east==short$east &
> long$north==short$north]
> }
> 
> How could I avoid this loop?
> 
> Thanks and regards,
> 
> Javier
> --
> 
> Javier García-Pintado
> Institute of Earth Sciences Jaume Almera (CSIC)
> Lluis Sole Sabaris s/n, 08028 Barcelona
> Phone: +34 934095410
> Fax:   +34 934110012
> e-mail:jgarcia at ija.csic.es 
> 
> 
> 
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> 
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