Top or bottom n elements of a vector — which_top

Return the indices of the top or bottom abs(n) elements of a vector, with several methods for resolving ties.

Usage

which_top_n(x, n, tied = c("given", "all", "none"))

Arguments

x: a vector on which rank() can be evaluated.
n: the number of elements to attempt to select; if positive top n are selected, and if negative bottom -n.
tied: a string to specify how to handle multiple elements tied for n'th place: all or none to include all or none of the tied elements, returning a longer or shorter vector than n, respectively; given (the default) to use the order in which the elements are found in x.

Value

An integer vector of indices on x, with an attribute attr(, "tied") with the indicies of the tied elements (possibly empty).

Examples


(x <- rep(1:4, 1:4))
#>  [1] 1 2 2 3 3 3 4 4 4 4

stopifnot(identical(which_top_n(x, 5, "all"), structure(4:10, tied = 4:6)))
stopifnot(identical(which_top_n(x, 5, "none"), structure(7:10, tied = 4:6)))
stopifnot(identical(which_top_n(x, 5), structure(6:10, tied = 4:6)))

stopifnot(identical(which_top_n(x, -5, "all"), structure(1:6, tied = 4:6)))
stopifnot(identical(which_top_n(x, -5, "none"), structure(1:3, tied = 4:6)))
stopifnot(identical(which_top_n(x, -5), structure(1:5, tied = 4:6)))