Description Usage Arguments Details Value Examples
These functions power select()
and rename()
.
1 2 3 | select_vars(vars, ..., include = character(), exclude = character())
rename_vars(vars, ..., strict = TRUE)
|
vars |
A character vector of existing column names. |
..., args |
Expressions to compute These arguments are automatically quoted and
evaluated in a context where elements of
Note that except for |
include, exclude |
Character vector of column names to always include/exclude. |
strict |
If |
For historic reasons, the vars
and include
arguments are not
prefixed with .
. This means that any argument starting with v
might partial-match on vars
if it is not explicitly named. Also
...
cannot accept arguments named exclude
or include
. You can
enquose and splice the dots to work around these limitations (see
examples).
A named character vector. Values are existing column names, names are new names.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | # Keep variables
select_vars(names(iris), everything())
select_vars(names(iris), starts_with("Petal"))
select_vars(names(iris), ends_with("Width"))
select_vars(names(iris), contains("etal"))
select_vars(names(iris), matches(".t."))
select_vars(names(iris), Petal.Length, Petal.Width)
select_vars(names(iris), one_of("Petal.Length", "Petal.Width"))
df <- as.data.frame(matrix(runif(100), nrow = 10))
df <- df[c(3, 4, 7, 1, 9, 8, 5, 2, 6, 10)]
select_vars(names(df), num_range("V", 4:6))
# Drop variables
select_vars(names(iris), -starts_with("Petal"))
select_vars(names(iris), -ends_with("Width"))
select_vars(names(iris), -contains("etal"))
select_vars(names(iris), -matches(".t."))
select_vars(names(iris), -Petal.Length, -Petal.Width)
# Rename variables
select_vars(names(iris), petal_length = Petal.Length)
select_vars(names(iris), petal = starts_with("Petal"))
# Rename variables preserving all existing
rename_vars(names(iris), petal_length = Petal.Length)
# You can unquote names or formulas (or lists of)
select_vars(names(iris), !!! list(quo(Petal.Length)))
select_vars(names(iris), !! quote(Petal.Length))
# The .data pronoun is available:
select_vars(names(mtcars), .data$cyl)
select_vars(names(mtcars), .data$mpg : .data$disp)
# However it isn't available within calls since those are evaluated
# outside of the data context. This would fail if run:
# select_vars(names(mtcars), identical(.data$cyl))
# If you're writing a wrapper around select_vars(), pass the dots
# via splicing to avoid matching dotted arguments to select_vars()
# named arguments (`vars`, `include` and `exclude`):
wrapper <- function(...) {
select_vars(names(mtcars), !!! quos(...))
}
# This won't partial-match on `vars`:
wrapper(var = cyl)
# This won't match on `include`:
wrapper(include = cyl)
|
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