dplyr (version 0.5.0)

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.

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 given the position of the matched variables.

Examples

iris <- tbl_df(iris) # so it prints a little nicer
select(iris, starts_with("Petal"))
select(iris, ends_with("Width"))
select(iris, contains("etal"))
select(iris, matches(".t."))
select(iris, Petal.Length, Petal.Width)
select(iris, everything())
vars <- c("Petal.Length", "Petal.Width")
select(iris, one_of(vars))