[R] question regarding vector ops

[Rajarshi Guha]

Hi,
  I was playing with some code and came upon this situation.

> x <- c(1, rep(0,9))
> x
 [1] 1 0 0 0 0 0 0 0 0 0
> idx <- 1:10
> x[idx] <- x[idx] + 1
> x
 [1] 2 1 1 1 1 1 1 1 1 1

This is expected. But if I do:

> x <- c(1, rep(0,9))
> x
 [1] 1 0 0 0 0 0 0 0 0 0
> idx <- rep(0,10)
> idx
 [1] 0 0 0 0 0 0 0 0 0 0
> x[idx] <- x[idx] +1
> x
 [1] 1 0 0 0 0 0 0 0 0 0

I was expoecting that when all the elements of idx are set to 0,
x[0] would become 11.

Could somebody explain why this behavior occurs?

Thanks,


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Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
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