# Turn continuous data into discrete bins This is a cheapr version of `cut.numeric()` which is more efficient and prioritises pretty-looking breaks by default through the use of `get_breaks()`. Out-of-bounds values can be included naturally through the `include_oob` argument. Left-closed (right-open) intervals are returned by default in contrast to cut's default right-closed intervals. Furthermore there is flexibility in formatting the interval bins, allowing the user to specify formatting functions and symbols for the interval close and open symbols. ```r as_discrete(x, ...) ## S3 method for class 'numeric' as_discrete( x, breaks = if (left_closed) get_breaks(x) else rev_(-get_breaks(-x)), left_closed = TRUE, include_endpoint = FALSE, include_oob = FALSE, ordered = FALSE, intv_start_fun = prettyNum, intv_end_fun = prettyNum, intv_closers = c("[", "]"), intv_openers = c("(", ")"), intv_sep = ",", inf_label = NULL, ... ) ## S3 method for class 'integer64' as_discrete(x, ...) ``` ## Arguments - `x`: A numeric vector. - `...`: Extra arguments passed onto methods. - `breaks`: Break-points. The default option creates pretty looking breaks. Unlike `cut()`, the `breaks` arg cannot be a number denoting the number of breaks you want. To generate breakpoints this way use `get_breaks()`. - `left_closed`: Left-closed intervals or right-closed intervals? - `include_endpoint`: Include endpoint? Default is `FALSE`. - `include_oob`: Include out-of-bounds values? Default is `FALSE`. This is equivalent to `breaks = c(breaks, Inf)` or `breaks = c(-Inf, breaks)` when `left_closed = FALSE`. If `include_endpoint = TRUE`, the endpoint interval is prioritised before the out-of-bounds interval. This behaviour cannot be replicated easily with `cut()`. For example, these 2 expressions are not equivalent: ``` cut(10, c(9, 10, Inf), right = F, include.lowest = T) != as_discrete(10, c(9, 10), include_endpoint = T, include_oob = T) ``` - `ordered`: Should result be an ordered factor? Default is `FALSE`. - `intv_start_fun`: Function used to format interval start points. - `intv_end_fun`: Function used to format interval end points. - `intv_closers`: A length 2 character vector denoting the symbol to use for closing either left or right closed intervals. - `intv_openers`: A length 2 character vector denoting the symbol to use for opening either left or right closed intervals. - `intv_sep`: A length 1 character vector used to separate the start and end points. - `inf_label`: Label to use for intervals that include infinity. If left `NULL` the Unicode infinity symbol is used. ## Returns A factor of discrete bins (intervals of start/end pairs). ## Examples ```r library(cheapr) # `as_discrete()` is very similar to `cut()` # but more flexible as it allows you to supply # formatting functions and symbols for the discrete bins # Here is an example of how to use the formatting functions to # categorise age groups nicely ages <- 1:100 age_group <- function(x, breaks){ age_groups <- as_discrete( x, breaks = breaks, intv_sep = "-", intv_end_fun = function(x) x - 1, intv_openers = c("", ""), intv_closers = c("", ""), include_oob = TRUE, ordered = TRUE ) # Below is just renaming the last age group lvls <- levels(age_groups) n_lvls <- length(lvls) max_ages <- paste0(max(breaks), "+") attr(age_groups, "levels") <- c(lvls[-n_lvls], max_ages) age_groups } age_group(ages, seq(0, 80, 20)) age_group(ages, seq(0, 25, 5)) age_group(ages, 5) # To closely replicate `cut()` with `as_discrete()` we can use the following cheapr_cut <- function(x, breaks, right = TRUE, include.lowest = FALSE, ordered.result = FALSE){ if (length(breaks) == 1){ breaks <- get_breaks(x, breaks, pretty = FALSE, expand_min = FALSE, expand_max = FALSE) adj <- diff(range(breaks)) * 0.001 breaks[1] <- breaks[1] - adj breaks[length(breaks)] <- breaks[length(breaks)] + adj } as_discrete(x, breaks, left_closed = !right, include_endpoint = include.lowest, ordered = ordered.result, intv_start_fun = function(x) formatC(x, digits = 3, width = 1), intv_end_fun = function(x) formatC(x, digits = 3, width = 1)) } x <- rnorm(100) cheapr_cut(x, 10) identical(cut(x, 10), cheapr_cut(x, 10)) ``` ## See Also bin get_breaks

as_discrete function