Case statements applying a function to all inputs
fn_case(x, fn, ..., preserve = FALSE, default = NA)A vector
A function to apply to the left-hand side of each formula in ...
Either a quoted or unquoted function name, an anonymous function, or
a purrr-style formula.
The function should take two inputs, the first being x and the second
being the left-hand side of the formula.
The function should return a logical vector, either of length 1 or the same
length as x.
<dynamic-dots> A sequence of two-sided
formulas or named arguments.
Formulas: Elements of x that return TRUE when passed to fn with
the left hand side (LHS) of each formula will be replaced with the value in
the right hand side (RHS).
The LHS must evaluate to a logical vector when passed to fn with x.
The RHS must be of length 1 or the same length as all other RHS.
Named arguments: named arguments are passed as additional arguments
to the function fn.
If TRUE, unmatched elements of x will be returned
unmodified.
(The elements may have their type coerced to be compatible with
replacement values.)
If FALSE, unmatched elements of x will be replaced with default.
Defaults to FALSE.
If preserve is FALSE, a value to replace unmatched
elements of x.
Defaults to NA.
A vector of length 1 or n, matching the length of the logical input or output vectors. Inconsistent lengths will generate an error.
fn_case_fct() to return a factor and
fn_case_list() to return a list
fn_switch_case(), which applies a function to each formula's LHS,
but not x
switch_case(), a simpler alternative for exact matching
grep_case(), a simpler alternative for regex pattern matching
in_case(), a pipeable alternative to dplyr::case_when()
# Replicate switch_case()
parties <- sample(c("d", "r", "i", "g", "l"), 20, replace = TRUE)
fn_case(
parties,
fn = `%in%`,
"d" ~ "Democrat",
"r" ~ "Republican",
"i" ~ "Independent",
"g" ~ "Green",
"l" ~ "Libertarian"
)
#> [1] "Libertarian" "Green" "Libertarian" "Green" "Democrat"
#> [6] "Libertarian" "Libertarian" "Libertarian" "Republican" "Independent"
#> [11] "Independent" "Libertarian" "Libertarian" "Green" "Libertarian"
#> [16] "Republican" "Green" "Republican" "Independent" "Democrat"
# Replicate grep_case()
countries <- c(
"France", "Ostdeutschland", "Westdeutschland", "Nederland",
"Belgie (Vlaanderen)", "Belgique (Wallonie)", "Luxembourg", "Italia"
)
fn_case(
countries,
fn = function(x, pattern, ...) {grepl(pattern, x, ...)},
"Deutschland" ~ "Germany",
"Belgi(qu)?e" ~ "Belgium",
"Nederland" ~ "Netherlands",
"Italia" ~ "Italy",
preserve = TRUE,
ignore.case = TRUE
)
#> [1] "France" "Germany" "Germany" "Netherlands" "Belgium"
#> [6] "Belgium" "Luxembourg" "Italy"
fn_case(
countries,
fn = ~ grepl(.y, .x),
"Deutschland" ~ "Germany",
"Belgi(qu)?e" ~ "Belgium",
"Nederland" ~ "Netherlands",
"Italia" ~ "Italy",
preserve = TRUE,
ignore.case = TRUE
)
#> [1] "France" "Ostdeutschland" "Westdeutschland" "Netherlands"
#> [5] "Belgium" "Belgium" "Luxembourg" "Italy"
# Recode values in a range
time <- runif(10, 1, 12)
hours <- time %/% 1
minutes <- time %% 1 * 60
hours <- hours %>%
if_case(minutes > 32.5, (. + 1) %% 12, .) %>%
switch_case(0 ~ 12, preserve = TRUE)
minutes %>%
fn_case(
fn = ~ abs(.x - .y) <= 2.5,
0 ~ "o'clock",
60 ~ "o'clock",
30 ~ "half past",
15 ~ "quarter past",
45 ~ "quarter to",
5 ~ "five past",
10 ~ "ten past",
20 ~ "twenty past",
25 ~ "twenty-five past",
55 ~ "five to",
50 ~ "ten to",
40 ~ "twenty to",
35 ~ "twenty-five to"
) %>%
switch_case(
"o'clock" ~ paste(hours, .),
default = paste(., hours)
)
#> [1] "twenty-five past 11" "3 o'clock" "twenty-five past 3"
#> [4] "half past 8" "half past 6" "five past 8"
#> [7] "quarter past 8" "five past 2" "twenty-five past 9"
#> [10] "half past 9"
# Replicate vctrs::vec_ptype_abbr() (used for tibble column labels)
# Based on a contribution by Patrice Kiener
in_herits <- function(x) {
fn_case(
x,
fn = inherits,
"factor" ~ "fct",
"character" ~ "chr",
"numeric" ~ "dbl",
"integer" ~ "int",
"logical" ~ "lgl",
"complex" ~ "cpl",
"raw" ~ "raw",
"matrix" ~ "mat",
"array" ~ "arr",
"data.frame" ~ "df",
"list" ~ "lst",
"function" ~ "fn",
default = class(x)[[1]]
)
}
in_herits(1:3)
#> [1] "int"
in_herits(letters[1:3])
#> [1] "chr"
in_herits(fn_case)
#> [1] "fn"