klist: Create a List With Unique Keys (Named or Unnamed)

In keylist: Lightweight List Extensions that Enforce Unique Keys

Create a List With Unique Keys (Named or Unnamed)

Description

Create a named/unnamed list with unique keys, erroring if any duplicate keys (names) are found.

Usage

klist(...)

is.klist(x)

as.klist(x, ...)

## Default S3 method:
as.klist(x, ..., .recursive = FALSE)

## S3 replacement method for class 'klist'
names(x) <- value

## S3 method for class 'klist'
c(...)

Arguments

...	for klist: objects, possibly named, for as.klist: passed to other methods.
x	object to be coerced or tested.
.recursive	boolean indicating whether to recursively validate nested lists. If TRUE then all nested lists will be validated and converted to klists, if FALSE then only the top level list will be validated and converted to a klist.
value	a character vector of up to the same length as x, or NULL. Resulting names must be unique.

Details

⁠names<-⁠ method for klist objects will apply the names and then validate that the resulting names are unique.

c.klist method will combine the objects and then validate that the resulting klist's names are unique.

For a list with unique keys of all names, see knlist.

Value

A list object of class klist. For is.klist() a boolean.

Note

klists compare names using C's strcmp function.

as.list and as.vector methods for klist objects remove the class and return a base R list or vector.

See Also

knlist and keylist.

Examples

klist(a = 1, 2, b = 3)
try(klist(1, a = 2, a = 1)) # duplicate keys not allowed

# objects within a klist are not subject to validation
klist(1, list(a = 1, a = 2))
try(klist(1, klist(a = 1, a = 2))) # but nested klists are

# recursively validate and convert to klist
x <- list(1, list(1, 2))
x <- as.klist(x, .recursive = TRUE)
class(x[[2]]) # nested list is now a klist

is.klist(klist(1)) # TRUE

try(names(x) <- c("a", "a")) # names are validated when changed

# c() method for klist objects also validates
try(c(klist(a = 1), list(a = 3)))

keylist documentation built on April 27, 2026, 5:11 p.m.