is.na R中NaN值的状态

所以我正在开发这个功能

#' Disambiguated Equality operator between two vectors that may contain NA's
#'
#' Forces the equality result to be TRUE if both corresponding vector elements are either equal, or both NA.
#' @param x vector of any type compatible with is.na and ==.
#' @param y vector of any type compatible with is.na and ==.
#' @export
#' @examples 
#' c(NA, 1:5) %==% c(NA, 1:3,"nope", NA) #[1]  TRUE  TRUE  TRUE  TRUE FALSE FALSE

gp.is.equal.force <- `%==%` <- function(x, y, vect = T) {
  res <- (is.na(x) & is.na(y)) | (!is.na(x) & !is.na(y) & x == y)
  if (!vect) res <- all(res)
  res
}

我注意到,在R版本4.3.2(2023-10-31)中,NaN值出现了一种我意想不到的行为——“眼孔”。

> is.na(NaN) # [1] TRUE
> is.na(c(NaN, 5)) # [1]  TRUE FALSE
> is.na(c(NaN, NA)) # [1] TRUE TRUE
> is.nan(c(NaN, NA)) # [1]  TRUE FALSE
> is.na(c(NaN, as.factor("abc"))) # [1]  TRUE FALSE
> is.nan(c(NaN, 5)) # [1]  TRUE FALSE

然而,到目前为止一切都很好:

> is.na(c(NA, NaN, "abc")) # [1]  TRUE FALSE FALSE
> is.nan(c(NA, NaN, "abc")) # [1] FALSE FALSE FALSE
> is.nan(c(NaN, "abc")) #[1] FALSE FALSE

似乎在添加 character s的加入以某种方式打破了逻辑 NaN 价值观 这不是很奇怪吗?