icuSetCollate {base} | R Documentation |
Setup Collation by ICU
Description
Controls the way collation is done by ICU (an optional part of the R build).
Usage
icuSetCollate(...)
Arguments
... |
Named arguments, see ‘Details’. |
Details
Optionally, R can be built to collate character strings by ICU
(http://www.icu-project.org). For such systems,
icuSetCollate
can be used to tune the way collation is done.
On other builds calling this function does nothing, with a warning.
Possible arguments are
locale
:A character string such as
"da_DK"
giving the country whose collation rules are to be used. If present, this should be the first argument.case_first
:"upper"
,"lower"
or"default"
, asking for upper- or lower-case characters to be sorted first. The default is usually lower-case first, but not in all languages (see the Danish example).alternate_handling
:Controls the handling of ‘variable’ characters (mainly punctuation and symbols). Possible values are
"non_ignorable"
(primary strength) and"shifted"
(quaternary strength).strength
:Which components should be used? Possible values
"primary"
,"secondary"
,"tertiary"
(default),"quaternary"
and"identical"
.french_collation
:In a French locale the way accents affect collation is from right to left, whereas in most other locales it is from left to right. Possible values
"on"
,"off"
and"default"
.normalization
:Should strings be normalized? Possible values
"on"
and"off"
(default). This affects the collation of composite characters.case_level
:An additional level between secondary and tertiary, used to distinguish large and small Japanese Kana characters. Possible values
"on"
and"off"
(default).hiragana_quaternary
:Possible values
"on"
(sort Hiragana first at quaternary level) and"off"
.
Only the first three are likely to be of interest except to those with a detailed understanding of collation and specialized requirements.
Some examples are case_level="on", strength="primary"
to ignore
accent differences, alternate_handling="shifted"
to ignore
space and punctuation characters.
See Also
Comparison, sort
The ICU user guide chapter on collation (http://www.icu-project.org/userguide/Collate_Intro.html).
Examples
x <- c("Aarhus", "aarhus", "safe", "test", "Zoo")
sort(x)
icuSetCollate(case_first="upper"); sort(x)
icuSetCollate(case_first="lower"); sort(x)
icuSetCollate(locale="da_DK", case_first="default"); sort(x)
icuSetCollate(locale="et_EE"); sort(x)