tidyselect (version 0.2.0)

select_helpers: Select helpers

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.

• last_col(): last variable, possibly with an offset.

Usage

starts_with(match, ignore.case = TRUE, vars = peek_vars())
ends_with(match, ignore.case = TRUE, vars = peek_vars())
contains(match, ignore.case = TRUE, vars = peek_vars())
matches(match, ignore.case = TRUE, vars = peek_vars())
num_range(prefix, range, width = NULL, vars = peek_vars())
one_of(..., .vars = peek_vars())
everything(vars = peek_vars())
last_col(offset = 0, vars = peek_vars())

Arguments

match

A string.

ignore.case

If TRUE, the default, ignores case when matching names.

vars, .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.

offset

Set it to n to select the nth var from the end.

Value

An integer vector giving the position of the matched variables.

Examples

# NOT RUN {
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_select(nms, last_col())
vars_select(nms, last_col(offset = 2))

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