pkgmaker 0.16

Expanding Lists

Usage

expand_list(x, ..., .exact = TRUE, .names = !.exact)

expand_dots(..., .exclude = NULL)

Arguments

x
input list
...
extra named arguments defining the default items. A list of default values can also be passed as a a single unnamed argument.
.exact
logical that indicates if the names in x should be partially matched against the defaults.
.names
logical that only used when .exact=FALSE and indicates that the names of items in x that partially match some defaults should be expanded in the returned list.
.exclude
optional character vector of argument names to exclude from expansion.

Value

a list

Description

expand_list expands a named list with a given set of default items, if these are not already in the list, partially matching their names.

expand_dots expands the ... arguments of the function in which it is called with default values, using expand_list. It can only be called from inside a function.

Examples

expand_list(list(a=1, b=2), c=3)



$a
[1] 1

$b
[1] 2

$c
[1] 3


expand_list(list(a=1, b=2, c=4), c=3)



$a
[1] 1

$b
[1] 2

$c
[1] 4


# with a list
expand_list(list(a=1, b=2), list(c=3, d=10))



$a
[1] 1

$b
[1] 2

$c
[1] 3

$d
[1] 10


# no partial match
expand_list(list(a=1, b=2, c=5), cd=3)



$a
[1] 1

$b
[1] 2

$c
[1] 5

$cd
[1] 3


# partial match with names expanded
expand_list(list(a=1, b=2, c=5), cd=3, .exact=FALSE)



$a
[1] 1

$b
[1] 2

$cd
[1] 5


# partial match without expanding names
expand_list(list(a=1, b=2, c=5), cd=3, .exact=FALSE, .names=FALSE)



$a
[1] 1

$b
[1] 2

$c
[1] 5


# works also inside a function to expand a call with default arguments
f <- function(...){
	cl  <- match.call()
	expand_list(cl, list(a=3, b=4), .exact=FALSE)
}

f()



f(a = 3, b = 4)

f(c=1)



f(c = 1, a = 3, b = 4)

f(a=2)



f(a = 2, b = 4)

f(c=1, a=2)



f(c = 1, a = 2, b = 4)

# expanding dot arguments
f <- function(...){
	expand_dots(list(a=2, bcd='a', xxx=20), .exclude='xxx')
}

# add default value for all arguments
f()



$a
[1] 2

$bcd
[1] "a"


# add default value for `bcd` only
f(a=10)



$a
[1] 10

$bcd
[1] "a"


# expand names
f(a=10, b=4)



$a
[1] 10

$bcd
[1] 4