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

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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

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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))

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