strcoll: Compare Strings#
Description#
These functions provide means to compare strings in any locale using the Unicode collation algorithm.
Usage#
strcoll(
e1,
e2,
locale = NULL,
strength = 3L,
alternate_shifted = FALSE,
french = FALSE,
uppercase_first = NA,
case_level = FALSE,
normalisation = FALSE,
numeric = FALSE
)
e1 %x<% e2
e1 %x<=% e2
e1 %x==% e2
e1 %x!=% e2
e1 %x>% e2
e1 %x>=% e2
Arguments#
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character vector whose corresponding elements are to be compared |
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Details#
These functions are fully vectorised with respect to both arguments.
For a locale-insensitive behaviour like that of strcmp
from the standard C library, call strcoll(e1, e2, locale="C", strength=4L, normalisation=FALSE)
. However, some normalisation will still be performed.
Value#
strcoll
returns an integer vector representing the comparison results: if a string in e1
is smaller than the corresponding string in e2
, the corresponding result will be equal to -1
, and 0
if they are canonically equivalent, as well as 1
if the former is greater than the latter.
The binary operators call strcoll
with default arguments and return logical vectors.
Differences from Base R#
Replacements for base Comparison operators implemented with stri_cmp
.
collation in different locales is difficult and non-portable across platforms [fixed here – using services provided by ICU]
overloading
`<.character`
has no effect in R, because S3 method dispatch is done internally with hard-coded support for character arguments. We could have replaced the generic`<`
with the one that callsUseMethod
, but it feels like a too intrusive solution [fixed by introducing the`%x<%`
operator]
See Also#
The official online manual of stringx at https://stringx.gagolewski.com/
Related function(s): xtfrm
Examples#
# lexicographic vs. numeric sort
strcoll("100", c("1", "10", "11", "99", "100", "101", "1000"))
## [1] 1 1 -1 -1 0 -1 -1
strcoll("100", c("1", "10", "11", "99", "100", "101", "1000"), numeric=TRUE)
## [1] 1 1 1 1 0 -1 -1
strcoll("hladn\u00FD", "chladn\u00FD", locale="sk_SK")
## [1] -1