select_helpers: Select helpers

In sctyner/dplyr050: A Grammar of Data Manipulation

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))

sctyner/dplyr050 documentation built on May 17, 2019, 2:22 p.m.