dot_mutate: Evaluate an arbitrary mutating expression in a magrittr pipe

In DarwinAwardWinner/rctutils: Utility functions by Ryan C. Thompson

Evaluate an arbitrary mutating expression in a magrittr pipe

Description

Evaluate an arbitrary mutating expression in a magrittr pipe

Usage

dot_mutate(x, expr)

Arguments

x	The object to assign into. (Typically this argument is delivered via %\>%().)
expr	The expression to be evaluated with . set to x. Typically this expression modifies . in some way, e.g. by performing an assignment with . on the left-hand side.

Value

The value of x after evaluating expr.

As usual, x, the object being passed in, should be referenced in expr as ..

Note that this function uses the lazyeval package rather than its apparent successor, rlang, because rlang doesn't support interpolating expressions on the left-hand-side of an assignment operation: https://github.com/r-lib/rlang/issues/212.

Examples

library(magrittr)

# Returns the entire list, not just a single element
list(a = 1, b = 2, c = 3) %>%
  dot_mutate(.$d <- 4) %>%
  dot_mutate({ .$e <- 5; .$f <- 6})

# Compare:
list(a = 1, b = 2, c = 3) %>%
  {.$d <- 4} %>%
  print

DarwinAwardWinner/rctutils documentation built on July 22, 2022, 5:19 a.m.