Re: [R] indexing a vector starting from 0

From: Peter Dalgaard <p.dalgaard_at_biostat.ku.dk>
Date: Mon 25 Jul 2005 - 06:50:22 EST

Federico Calboli <f.calboli@imperial.ac.uk> writes:

> Hi All,
>
> I would like to ask if it possible to start indexing a vector from 0:
>
> x = 1:10
>
> y = c(0,0,3,4,5,6,0,8,9,10)
>
> I need to use y as an index to extract the values of x, BUT I cannot
> cull/transform the 0s. What I would like is to start counting the
> elements of x 0:9 rather than 1:10. Would this be at all possible?

There's a 0array package on CRAN, but why not just add 1 to the index?

> x[y+1]
 [1] 1 1 4 5 6 7 1 9 10 NA

In general, 0-based indexing is possible, but messes with other things in R, most obviously negative indexes, but also constructions that use match(...., nomatch=0)

-- 
   O__  ---- Peter Dalgaard             ุster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

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Received on Mon Jul 25 06:57:06 2005

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