dplyr_tidy_select: Argument type: tidy-select

dplyr_tidy_selectR Documentation

Argument type: tidy-select

Description

This page the describes the <tidy-select> argument modifier which indicates the argument supports tidy selections. Tidy selection provides a concise dialect of R for selecting variables based on their names or properties.

Tidy selection is a variant of tidy evaluation. This means that inside functions, tidy-select arguments require special attention, as described in the Indirection section. If you've never heard of tidy evaluation before, start with vignette("programming").

Overview of selection features

Tidyverse selections implement a dialect of R where operators make it easy to select variables:

  • : for selecting a range of consecutive variables.

  • ! for taking the complement of a set of variables.

  • & and | for selecting the intersection or the union of two sets of variables.

  • c() for combining selections.

In addition, you can use selection helpers. Some helpers select specific columns:

  • everything(): Matches all variables.

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

These helpers select variables by matching patterns in their names:

  • starts_with(): Starts with a prefix.

  • ends_with(): Ends with a suffix.

  • contains(): Contains a literal string.

  • matches(): Matches a regular expression.

  • num_range(): Matches a numerical range like x01, x02, x03.

These helpers select variables from a character vector:

  • all_of(): Matches variable names in a character vector. All names must be present, otherwise an out-of-bounds error is thrown.

  • any_of(): Same as all_of(), except that no error is thrown for names that don't exist.

This helper selects variables with a function:

  • where(): Applies a function to all variables and selects those for which the function returns TRUE.

Indirection

There are two main cases:

  • If you have a character vector of column names, use all_of() or any_of(), depending on whether or not you want unknown variable names to cause an error, e.g select(df, all_of(vars)), select(df, !any_of(vars)).

  • If you you want the user to supply a tidyselect specification in a function argument, embrace the function argument, e.g select(df, {{ vars }}).


dplyr documentation built on Sept. 1, 2022, 5:06 p.m.