Questioning lifecycle

The atomic vector constructors are equivalent to c() but:

  • They allow you to be more explicit about the output type. Implicit coercions (e.g. from integer to logical) follow the rules described in vector-coercion.

  • They use dynamic dots.

lgl(...)

int(...)

dbl(...)

cpl(...)

chr(...)

bytes(...)

Arguments

...

Components of the new vector. Bare lists and explicitly spliced lists are spliced.

Life cycle

  • All the abbreviated constructors such as lgl() will probably be moved to the vctrs package at some point. This is why they are marked as questioning.

  • Automatic splicing is soft-deprecated and will trigger a warning in a future version. Please splice explicitly with !!!.

Examples

# These constructors are like a typed version of c(): c(TRUE, FALSE)
#> [1] TRUE FALSE
lgl(TRUE, FALSE)
#> [1] TRUE FALSE
# They follow a restricted set of coercion rules: int(TRUE, FALSE, 20)
#> [1] 1 0 20
# Lists can be spliced: dbl(10, !!! list(1, 2L), TRUE)
#> [1] 10 1 2 1
# They splice names a bit differently than c(). The latter # automatically composes inner and outer names: c(a = c(A = 10), b = c(B = 20, C = 30))
#> a.A b.B b.C #> 10 20 30
# On the other hand, rlang's ctors use the inner names and issue a # warning to inform the user that the outer names are ignored: dbl(a = c(A = 10), b = c(B = 20, C = 30))
#> Warning: Outer names are only allowed for unnamed scalar atomic inputs
#> A B C #> 10 20 30
dbl(a = c(1, 2))
#> Warning: Outer names are only allowed for unnamed scalar atomic inputs
#> [1] 1 2
# As an exception, it is allowed to provide an outer name when the # inner vector is an unnamed scalar atomic: dbl(a = 1)
#> a #> 1
# Spliced lists behave the same way: dbl(!!! list(a = 1))
#> a #> 1
dbl(!!! list(a = c(A = 1)))
#> Warning: Outer names are only allowed for unnamed scalar atomic inputs
#> A #> 1
# bytes() accepts integerish inputs bytes(1:10)
#> [1] 01 02 03 04 05 06 07 08 09 0a
bytes(0x01, 0xff, c(0x03, 0x05), list(10, 20, 30L))
#> [1] 01 ff 03 05 0a 14 1e