Switch-style recoding of values with string pattern matching

grep_case(x, ..., preserve = FALSE, default = NA)

Arguments

x A vector <dynamic-dots> A sequence of two-sided formulas or named arguments. Formulas: Elements of x that match the regex pattern on the left hand side (LHS) of formulas will be replaced with the value in the right hand side (RHS). The LHS must evaluate to a character string. The RHS must be of length one. NULL inputs are ignored. Named arguments: named arguments are passed to grepl(). 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.

Value

A vector of the same length as x.

grep_case_fct() to return a factor and grep_case_list() to return a list

fn_case(), to apply a function other than grepl() to each case

switch_case() to recode values with exact matching

in_case(), a pipeable alternative to dplyr::case_when()

switch() and grepl(), which inspired this function

Examples

words <- c("caterpillar", "dogwood", "catastrophe", "dogma")

grep_case(
words,
"cat" ~ "feline",
"dog" ~ "canine"
)
#> [1] "feline" "canine" "feline" "canine"
caps_words <- c("caterpillar", "dogwood", "Catastrophe", "DOGMA")

grep_case(
caps_words,
"cat" ~ "feline",
"dog" ~ "canine",
ignore.case = TRUE
)
#> [1] "feline" "canine" "feline" "canine"
countries <- c(
"France", "Ostdeutschland", "Westdeutschland", "Nederland",
"Belgie (Vlaanderen)", "Belgique (Wallonie)", "Luxembourg", "Italia"
)

grep_case(
countries,
"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"