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Merge values of multiple variables per observation into one new variable.


  new_column = NULL,
  select = NULL,
  exclude = NULL,
  separator = "_",
  append = FALSE,
  remove_na = FALSE,
  ignore_case = FALSE,
  verbose = TRUE,
  regex = FALSE,



A data frame.


The name of the new column, as a string.


Variables that will be included when performing the required tasks. Can be either

  • a variable specified as a literal variable name (e.g., column_name),

  • a string with the variable name (e.g., "column_name"), or a character vector of variable names (e.g., c("col1", "col2", "col3")),

  • a formula with variable names (e.g., ~column_1 + column_2),

  • a vector of positive integers, giving the positions counting from the left (e.g. 1 or c(1, 3, 5)),

  • a vector of negative integers, giving the positions counting from the right (e.g., -1 or -1:-3),

  • one of the following select-helpers: starts_with(), ends_with(), contains(), a range using : or regex(""). starts_with(), ends_with(), and contains() accept several patterns, e.g starts_with("Sep", "Petal").

  • or a function testing for logical conditions, e.g. is.numeric() (or is.numeric), or any user-defined function that selects the variables for which the function returns TRUE (like: foo <- function(x) mean(x) > 3),

  • ranges specified via literal variable names, select-helpers (except regex()) and (user-defined) functions can be negated, i.e. return non-matching elements, when prefixed with a -, e.g. -ends_with(""), -is.numeric or -(Sepal.Width:Petal.Length). Note: Negation means that matches are excluded, and thus, the exclude argument can be used alternatively. For instance, select=-ends_with("Length") (with -) is equivalent to exclude=ends_with("Length") (no -). In case negation should not work as expected, use the exclude argument instead.

If NULL, selects all columns. Patterns that found no matches are silently ignored, e.g. extract_column_names(iris, select = c("Species", "Test")) will just return "Species".


See select, however, column names matched by the pattern from exclude will be excluded instead of selected. If NULL (the default), excludes no columns.


A character to use between values.


Logical, if FALSE (default), removes original columns that were united. If TRUE, all columns are preserved and the new column is appended to the data frame.


Logical, if TRUE, missing values (NA) are not included in the united values. If FALSE, missing values are represented as "NA" in the united values.


Logical, if TRUE and when one of the select-helpers or a regular expression is used in select, ignores lower/upper case in the search pattern when matching against variable names.


Toggle warnings.


Logical, if TRUE, the search pattern from select will be treated as regular expression. When regex = TRUE, select must be a character string (or a variable containing a character string) and is not allowed to be one of the supported select-helpers or a character vector of length > 1. regex = TRUE is comparable to using one of the two select-helpers, select = contains("") or select = regex(""), however, since the select-helpers may not work when called from inside other functions (see 'Details'), this argument may be used as workaround.


Currently not used.


data, with a newly created variable.

See also


d <- data.frame(
  x = 1:3,
  y = letters[1:3],
  z = 6:8
#>   x y z
#> 1 1 a 6
#> 2 2 b 7
#> 3 3 c 8
data_unite(d, new_column = "xyz")
#>     xyz
#> 1 1_a_6
#> 2 2_b_7
#> 3 3_c_8
data_unite(d, new_column = "xyz", remove = FALSE)
#>     xyz
#> 1 1_a_6
#> 2 2_b_7
#> 3 3_c_8
data_unite(d, new_column = "xyz", select = c("x", "z"))
#>   y xyz
#> 1 a 1_6
#> 2 b 2_7
#> 3 c 3_8
data_unite(d, new_column = "xyz", select = c("x", "z"), append = TRUE)
#>   x y z xyz
#> 1 1 a 6 1_6
#> 2 2 b 7 2_7
#> 3 3 c 8 3_8