[Convert numeric value to natural language approximation] #R

approx_num.R

#' @title Convert a numeric value into a natural language approximation string
#' 
#' @description 
#' This function takes a numeric value and returns a string that approximates the value in natural language.
#' 
#' @param x A numeric value.
#' 
#' @examples 
#' approx_num(0.5)
#' # [1] "increased by a half"
#' 
#' approx_num(1.35)
#' # [1] "increased by about 140%"
#' 
#' @return
approx_num <- function(x){

    xrnd1 <- round(x, 0)
    xrnd2 <- round(x*2,0)/2
    xrnd3 <- round(x*3,0)/3
    xrnd4 <- round(x*4,0)/4
    xrnd10 <- round(x*10,0)/10
    xrnd100 <- round(x*100,0)/100

    approx <- dplyr::case_when(
        x == -1 ~ paste0("decreased to zero"),
        x <= -0.95 ~ paste0("decreased to near zero"),
        x < -0.2 ~ paste0("decreased by about ", abs(xrnd10)*100, "%"),
        x < -0.1 ~ paste0("decreased slightly by ", abs(xrnd10)*100, "%"),
        x < 0.1 ~ paste0("overall did not significantly increase or decrease"),
        xrnd4*4 == 1 & abs(xrnd4 - x) <= abs(xrnd3-x) ~
         case_when(
            xrnd4 > x ~ "increased by almost a quarter",
            xrnd4 == x ~ "increased by a quarter",
            xrnd4 < x  ~ "increased by more than a quarter"),
            xrnd3*3 == 1 & abs(xrnd3 - x) <= abs(xrnd2-x) ~
             case_when(
                xrnd3 > x ~ "increased by almost a third",
                xrnd3 == x ~ "increased by a third",
                xrnd3 < x  ~ "increased by more than a third"),
                xrnd2*2 == 1 ~
                 case_when(
                    xrnd2 > x ~ "increased by almost half",
                    xrnd2 == x ~ "increased by a half",
                    xrnd2 < x ~ "increased by more than half"),
                    x < 0.85 ~ paste0("increased by about", xrnd10*100, "%"),
                    xrnd1 == xrnd2 ~
                     case_when(
                        xrnd2 > x ~ paste0("increased by almost ", xrnd2+1, "X"),
                        xrnd2 == x ~ paste0("increased by ", xrnd2+1, "X"),
                        xrnd2 < x ~ paste0("increased by more than ", xrnd2+1, "X")),
                        TRUE ~ paste0("increased by about ", xrnd10*100, "%")
    )

    return(approx)
}