[R] basic indexing
Duncan Murdoch
dmurdoch at pair.com
Wed Oct 10 04:22:26 CEST 2001
On Tue, 9 Oct 2001 21:00:32 -0400, you wrote:
>in stata this would be
>gen z=x[N-1]
In R use z <- c(NA, x[-length(x)])
This says that z is an NA followed by the x vector with the last
element left off. Another way is
z <- c(NA, x)
length(z) <- length(x)
>in stata this would be
>gen z=x[N-1] if y==8
In R you should probably use two statements for this. The first
constructs z as above, the second is
z[y != 8] <- NA
A one-liner is
z <- ifelse(y == 8, c(NA, x[-length(x)]), NA)
Duncan Murdoch
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