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Resulting strings are unique and consist only of the _ character, numbers, and letters. By default, the resulting strings will only consist of ASCII characters, but non-ASCII (e.g. Unicode) may be allowed by setting ascii = FALSE. Capitalization preferences can be specified using the case parameter.

For use on the names of a data.frame, e.g., in a %>% pipeline, call the convenience function clean_names().

When ascii = TRUE (the default), accented characters are transliterated to ASCII. For example, an "o" with a German umlaut over it becomes "o", and the Spanish character "enye" becomes "n".

The order of operations is: make replacements, (optional) ASCII conversion, remove initial spaces and punctuation, apply base::make.names(), apply snakecase::to_any_case((), and add numeric suffixes to resolve any duplicated names.

This function relies on snakecase::to_any_case() and can take advantage of its versatility. For instance, an abbreviation like "ID" can have its capitalization preserved by passing the argument abbreviations = "ID". See the documentation for snakecase::to_any_case() for more about how to use its features.

On some systems, not all transliterators to ASCII are available. If this is the case on your system, all available transliterators will be used, and a warning will be issued once per session indicating that results may be different when run on a different system. That warning can be disabled with options(janitor_warn_transliterators=FALSE).

If the objective of your call to make_clean_names() is only to translate to ASCII, try the following instead: stringi::stri_trans_general(x, id="Any-Latin;Greek-Latin;Latin-ASCII").


  case = "snake",
  replace = c(`'` = "", `"` = "", `%` = "_percent_", `#` = "_number_"),
  ascii = TRUE,
  use_make_names = TRUE,
  allow_dupes = FALSE,
  sep_in = "\\.",
  transliterations = "Latin-ASCII",
  parsing_option = 1,
  numerals = "asis",



A character vector of names to clean.


The desired target case (default is "snake") will be passed to snakecase::to_any_case() with the exception of "old_janitor", which exists only to support legacy code (it preserves the behavior of clean_names() prior to addition of the "case" argument (janitor versions <= 0.3.1). "old_janitor" is not intended for new code. See snakecase::to_any_case() for a wide variety of supported cases, including "sentence" and "title" case.


A named character vector where the name is replaced by the value.


Convert the names to ASCII (TRUE, default) or not (FALSE).


Should make.names() be applied to ensure that the output is usable as a name without quoting? (Avoiding make.names() ensures that the output is locale-independent but quoting may be required.)


Allow duplicates in the returned names (TRUE) or not (FALSE, the default).


(short for separator input) if character, is interpreted as a regular expression (wrapped internally into stringr::regex()). The default value is a regular expression that matches any sequence of non-alphanumeric values. All matches will be replaced by underscores (additionally to "_" and " ", for which this is always true, even if NULL is supplied). These underscores are used internally to split the strings into substrings and specify the word boundaries.


A character vector (if not NULL). The entries of this argument need to be elements of stringi::stri_trans_list() (like "Latin-ASCII", which is often useful) or names of lookup tables (currently only "german" is supported). In the order of the entries the letters of the input string will be transliterated via stringi::stri_trans_general() or replaced via the matches of the lookup table. When named character elements are supplied as part of `transliterations`, anything that matches the names is replaced by the corresponding value. You should use this feature with care in case of case = "parsed", case = "internal_parsing" and case = "none", since for upper case letters, which have transliterations/replacements of length 2, the second letter will be transliterated to lowercase, for example Oe, Ae, Ss, which might not always be what is intended. In this case you can make usage of the option to supply named elements and specify the transliterations yourself.


An integer that will determine the parsing_option.

  • 1: "RRRStudio" -> "RRR_Studio"

  • 2: "RRRStudio" -> "RRRS_tudio"

  • 3: "RRRStudio" -> "RRRSStudio". This will become for example "Rrrstudio" when we convert to lower camel case.

  • -1, -2, -3: These parsing_options's will suppress the conversion after non-alphanumeric values.

  • 0: no parsing


A character specifying the alignment of numerals ("middle", left, right, asis or tight). I.e. numerals = "left" ensures that no output separator is in front of a digit.


Arguments passed on to snakecase::to_any_case


character. (Case insensitive) matched abbreviations are surrounded by underscores. In this way, they can get recognized by the parser. This is useful when e.g. parsing_option 1 is needed for the use case, but some abbreviations but some substrings would require parsing_option 2. Furthermore, this argument also specifies the formatting of abbreviations in the output for the cases title, mixed, lower and upper camel. E.g. for upper camel the first letter is always in upper case, but when the abbreviation is supplied in upper case, this will also be visible in the output.

Use this feature with care: One letter abbreviations and abbreviations next to each other are hard to read and also not easy to parse for further processing.


(short for separator output) String that will be used as separator. The defaults are "_" and "", regarding the specified case. When length(sep_out) > 1, the last element of sep_out gets recycled and separators are incorporated per string according to their order.


A string. If not NULL, then duplicated names will get a suffix integer in the order of their appearance. The suffix is separated by the supplied string to this argument.


A string. If it is supplied, then each entry that matches "" will be replaced by the supplied string to this argument.


prefix (string).


postfix (string).


Returns the "cleaned" character vector.


# cleaning the names of a vector:
x <- structure(1:3, names = c("name with space", "TwoWords", "total $ (2009)"))
#> name with space        TwoWords  total $ (2009) 
#>               1               2               3 
names(x) <- make_clean_names(names(x))
x # now has cleaned names
#> name_with_space       two_words      total_2009 
#>               1               2               3 

# if you prefer camelCase variable names:
make_clean_names(names(x), "small_camel")
#> [1] "nameWithSpace" "twoWords"      "total2009"    

# similar to janitor::clean_names(poorly_named_df):
# not run:
# make_clean_names(names(poorly_named_df))