select_helpers: Select helpers

In lionel-/tidyselect: Select From a Set of Strings

Description

These functions allow you to select variables based on their names. * 'starts_with()': starts with a prefix * 'ends_with()': ends with a prefix * 'contains()': contains a literal string * 'matches()': matches a regular expression * 'num_range()': a numerical range like x01, x02, x03. * 'one_of()': variables in character vector. * 'everything()': all variables.

Usage

current_vars()

starts_with(match, ignore.case = TRUE, vars = current_vars())

ends_with(match, ignore.case = TRUE, vars = current_vars())

contains(match, ignore.case = TRUE, vars = current_vars())

matches(match, ignore.case = TRUE, vars = current_vars())

num_range(prefix, range, width = NULL, vars = current_vars())

one_of(..., vars = current_vars())

everything(vars = current_vars())

Arguments

match	A string.
ignore.case	If 'TRUE', the default, ignores case when matching names.
vars	A character vector of variable names. When called from inside [select()] these are automatically set to the names of the table.
prefix	A prefix that starts the numeric range.
range	A sequence of integers, like '1:5'
width	Optionally, the "width" of the numeric range. For example, a range of 2 gives "01", a range of three "001", etc.
...	One or more character vectors.

Value

An integer vector giving the position of the matched variables.

Examples

nms <- names(iris)
vars_select(nms, starts_with("Petal"))
vars_select(nms, ends_with("Width"))
vars_select(nms, contains("etal"))
vars_select(nms, matches(".t."))
vars_select(nms, Petal.Length, Petal.Width)
vars_select(nms, everything())

vars <- c("Petal.Length", "Petal.Width")
vars_select(nms, one_of(vars))

lionel-/tidyselect documentation built on May 14, 2019, 9:23 p.m.