[R] %+=% and eval.parent()

[Gabor Grothendieck]

Robin Hankin <rksh <at> soc.soton.ac.uk> writes:
> R> a <- matrix(1:9,3,3)
> But the following caught me off-guard:
> R> a <- matrix(1:9,3,3)
> R> a[a%%2==1] %+=% 1000*(1:5)

How about this way:

> a <- matrix(1:9,3,3)
> "plus<-" <- function(a,value) a+value
> plus(a[a%%2==1]) <- 1000*(1:5)
> a
     [,1] [,2] [,3]
[1,] 1001    4 4007
[2,]    2 3005    8
[3,] 2003    6 5009
>