sfsmisc (version 0.9-4)

inv.seq: Inverse seq() -- Short Expression for Index Vector

Description

Compute a short expression for a given integer vector, typically an index, that can be expressed shortly, using : etc.

Usage

inv.seq(i)

Arguments

i

vector of (usually increasing) integers.

Value

• an expression which can be eval()ed to return the original i.

See Also

rle for another kind of integer vector coding.

Examples

(rr <- inv.seq(i1 <- c(3:12, 20:24, 27, 30:33)))
eval(rr)
stopifnot(eval(rr) == i1)

e2 <- expression(c(20:13, 3:12, -1:-4, 27, 30:31))
(r2 <- inv.seq(i2 <- eval(e2)))
stopifnot(identical(e2,r2))