# R/weighted_ntile.R In hutils: Miscellaneous R Functions and Aliases

#### Documented in weighted_ntile

```#' Weighted (ranked) quantiles
#'
#' @param vector The vector for which quantiles are desired.
#' @param weights The weights associated with the vector. None should be \code{NA} or zero.
#' @param n The number of quantiles desired.
#' @return A vector of integers corresponding to the ntiles. (As in \code{dplyr::ntile}.)
#' @examples
#' weighted_ntile(1:10, n = 5)
#' weighted_ntile(1:10, weights = c(rep(4, 5), rep(1, 5)), n = 5)
#' @export
#' @details With a short-length vector, or with weights of a high variance, the results may be unexpected.

weighted_ntile <- function(vector, weights = rep(1, times = length(vector)), n) {
if (missing(weights) || length(weights) <= 1L) {
v <- vector
# This line is basically from dplyr. MIT License
return(as.integer(n * {frank(v, ties.method = "first") - 1} / length(v) + 1))
}

min_w <- min(weights)
if (min_w < 0) {
stop("`weights` contained negative values. Ensure `weights` is non-negative.")
}

if (min_w == 0) {
warning("Some weights are zero. Maximum ntile may be incorrect.")
}

if (length(weights) != length(vector)) {
stop("`length(weights) = ", length(weights), "`, yet ",
"`length(vector) = ", length(vector), "`. ",
"`vector` and `weights` must have the same length.")
}

ov <- order(vector)
out <- as.integer(n * cumsum(shift(x = weights[ov], fill = 0)) / sum(weights))

if (last(out) >= n) {
warning("Some ntiles greater than n = ", n)
}
out[order(ov)] + 1L
}
```

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hutils documentation built on April 13, 2022, 5:23 p.m.