tidyeval: Tidy eval helpers

In timetk: A Tool Kit for Working with Time Series

Tidy eval helpers

Description

• sym creates a symbol from a string and syms creates a list of symbols from a character vector.

• enquo and enquos delay the execution of one or several function arguments. enquo() returns a single quoted expression, which is like a blueprint for the delayed computation. enquos() returns a list of such quoted expressions.

• expr quotes a new expression locally. It is mostly useful to build new expressions around arguments captured with enquo() or enquos(): expr(mean(!!enquo(arg), na.rm = TRUE)).

• as_name transforms a quoted variable name into a string. Supplying something else than a quoted variable name is an error.

  That's unlike as_label which also returns a single string but supports any kind of R object as input, including quoted function calls and vectors. Its purpose is to summarise that object into a single label. That label is often suitable as a default name.

  If you don't know what a quoted expression contains (for instance expressions captured with enquo() could be a variable name, a call to a function, or an unquoted constant), then use as_label(). If you know you have quoted a simple variable name, or would like to enforce this, use as_name().

To learn more about tidy eval and how to use these tools, visit the Metaprogramming section of Advanced R.

Value

Nothing returned. This is to document important functions from rlang that are used internal to this R package.

timetk documentation built on Nov. 2, 2023, 6:18 p.m.