Switch-style recoding of values with string pattern matching

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



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.


A vector of the same length as x.

See also

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


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"