mutate_all
Mutate multiple columns
Description
![[Superseded]](../help/figures/lifecycle-superseded.svg)
Scoped verbs (_if, _at, _all) have been superseded by the use of
across() in an existing verb. See vignette("colwise") for details.
The scoped variants of mutate() and transmute() make it easy to apply
the same transformation to multiple variables. There are three variants:
-
_all affects every variable
-
_at affects variables selected with a character vector or vars()
-
_if affects variables selected with a predicate function:
Usage
mutate_all(.tbl, .funs, ...) mutate_if(.tbl, .predicate, .funs, ...) mutate_at(.tbl, .vars, .funs, ..., .cols = NULL) transmute_all(.tbl, .funs, ...) transmute_if(.tbl, .predicate, .funs, ...) transmute_at(.tbl, .vars, .funs, ..., .cols = NULL)
Arguments
.tbl |
A |
.funs |
A function |
... |
Additional arguments for the function calls in
|
.predicate |
A predicate function to be applied to the columns
or a logical vector. The variables for which |
.vars |
A list of columns generated by |
.cols |
This argument has been renamed to |
Value
A data frame. By default, the newly created columns have the shortest names needed to uniquely identify the output. To force inclusion of a name, even when not needed, name the input (see examples for details).
Grouping variables
If applied on a grouped tibble, these operations are not applied
to the grouping variables. The behaviour depends on whether the
selection is implicit (all and if selections) or
explicit (at selections).
-
Grouping variables covered by explicit selections in
mutate_at()andtransmute_at()are always an error. Add-group_cols()to thevars()selection to avoid this:data %>% mutate_at(vars(-group_cols(), ...), myoperation)
Or remove
group_vars()from the character vector of column names:nms <- setdiff(nms, group_vars(data)) data %>% mutate_at(vars, myoperation)
-
Grouping variables covered by implicit selections are ignored by
mutate_all(),transmute_all(),mutate_if(), andtransmute_if().
Naming
The names of the new columns are derived from the names of the input variables and the names of the functions.
-
if there is only one unnamed function (i.e. if
.funsis an unnamed list of length one), the names of the input variables are used to name the new columns; -
for
_atfunctions, if there is only one unnamed variable (i.e., if.varsis of the formvars(a_single_column)) and.funshas length greater than one, the names of the functions are used to name the new columns; -
otherwise, the new names are created by concatenating the names of the input variables and the names of the functions, separated with an underscore
"_".
The .funs argument can be a named or unnamed list.
If a function is unnamed and the name cannot be derived automatically,
a name of the form "fn#" is used.
Similarly, vars() accepts named and unnamed arguments.
If a variable in .vars is named, a new column by that name will be created.
Name collisions in the new columns are disambiguated using a unique suffix.
Life cycle
The functions are maturing, because the naming scheme and the disambiguation algorithm are subject to change in dplyr 0.9.0.
See Also
Examples
iris <- as_tibble(iris)
# All variants can be passed functions and additional arguments,
# purrr-style. The _at() variants directly support strings. Here
# we'll scale the variables `height` and `mass`:
scale2 <- function(x, na.rm = FALSE) (x - mean(x, na.rm = na.rm)) / sd(x, na.rm)
starwars %>% mutate_at(c("height", "mass"), scale2)
# ->
starwars %>% mutate(across(c("height", "mass"), scale2))
# You can pass additional arguments to the function:
starwars %>% mutate_at(c("height", "mass"), scale2, na.rm = TRUE)
starwars %>% mutate_at(c("height", "mass"), ~scale2(., na.rm = TRUE))
# ->
starwars %>% mutate(across(c("height", "mass"), ~ scale2(.x, na.rm = TRUE)))
# You can also supply selection helpers to _at() functions but you have
# to quote them with vars():
iris %>% mutate_at(vars(matches("Sepal")), log)
iris %>% mutate(across(matches("Sepal"), log))
# The _if() variants apply a predicate function (a function that
# returns TRUE or FALSE) to determine the relevant subset of
# columns. Here we divide all the numeric columns by 100:
starwars %>% mutate_if(is.numeric, scale2, na.rm = TRUE)
starwars %>% mutate(across(where(is.numeric), ~ scale2(.x, na.rm = TRUE)))
# mutate_if() is particularly useful for transforming variables from
# one type to another
iris %>% mutate_if(is.factor, as.character)
iris %>% mutate_if(is.double, as.integer)
# ->
iris %>% mutate(across(where(is.factor), as.character))
iris %>% mutate(across(where(is.double), as.integer))
# Multiple transformations ----------------------------------------
# If you want to apply multiple transformations, pass a list of
# functions. When there are multiple functions, they create new
# variables instead of modifying the variables in place:
iris %>% mutate_if(is.numeric, list(scale2, log))
iris %>% mutate_if(is.numeric, list(~scale2(.), ~log(.)))
iris %>% mutate_if(is.numeric, list(scale = scale2, log = log))
# ->
iris %>%
as_tibble() %>%
mutate(across(where(is.numeric), list(scale = scale2, log = log)))
# When there's only one function in the list, it modifies existing
# variables in place. Give it a name to instead create new variables:
iris %>% mutate_if(is.numeric, list(scale2))
iris %>% mutate_if(is.numeric, list(scale = scale2))