[R] Finding indices with a certain property

[Peter Dalgaard BSA]

Göran Broström <gb at stat.umu.se> writes:

> I want the indices  i  for which  x[i] < 0 (say):
> 
> > x <- c(1, -1, 3, 3, -2)
> > where.negative(x)
> [1] 2 5
> 
> Surely  where.negative  is something simple, but how?

How about something like this?

> indices<-function(x)seq(along=x)[x]
> x <- c(1, -1, 3, 3, -2)
> indices(x<0)
[1] 2 5


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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