char_map
Split a Character Vector into its Unique Elements and a Mapping on These
Description
This is implemented using a radix sort on the CHARSXPs directly, i.e. on the
addresses of the strings in the global string cache. Hence, in contrast to
unique, this function does not consider two strings equal
which differ only in their encoding. Also, the order of the unique elements
is undefined.
Usage
char_map(x) map2char(map)
Arguments
x |
a character vector. Long vectors are supported. |
map |
an object as returned by |
Value
char_map returns an S3 object of class "char_map", which is a
list with the following elements: (chars) the unique set of strings in
x in undefined order, (idx) an integer (or - for long vectors -
double) vector such that map$chars[map$idx] is identical to x
(except maybe for attributes), (attributes) the attributes of x as a
shallow copy of the corresponding pairlist.
map2char returns a character vector identical to x,
including attributes.
Windows Support
Fully supported on Windows.
Lifecycle
![options:
alt='[Stable]'](../help/figures/lifecycle-stable.svg)
Examples
x <- sample(letters, 100, replace = TRUE) map <- char_map(x) stopifnot(identical(x, map$chars[map$idx])) names(x) <- 1:100 stopifnot(identical(x, map2char(char_map(x))))