stringi (version 0.2-5)

stri_compare: Compare Strings with or without Collation

Description

These functions may be used to determine if two strings are equal, canonically equivalent (this is performed in a way more clever fashion than when testing for equality), or to check whether they appear in a specific lexicographic order.

Usage

stri_compare(e1, e2, opts_collator = NULL)
stri_cmp(e1, e2, opts_collator = NULL)
stri_cmp_eq(e1, e2)
stri_cmp_neq(e1, e2)
stri_cmp_equiv(e1, e2, opts_collator = NULL)
stri_cmp_nequiv(e1, e2, opts_collator = NULL)
stri_cmp_lt(e1, e2, opts_collator = NULL)
stri_cmp_gt(e1, e2, opts_collator = NULL)
stri_cmp_le(e1, e2, opts_collator = NULL)
stri_cmp_ge(e1, e2, opts_collator = NULL)

Arguments

e1,e2

character vectors or objects coercible to character vectors

opts_collator

a named list with ICU Collator's options as generated with stri_opts_collator, NULL for default collation options.

Value

• The stri_cmp and stri_compare functions return an integer vector with comparison results of corresponding pairs of elements in e1 and e2: -1 if e1[...] < e2[...], 0 if they are canonically equivalent, and 1 if greater.

  The other functions return a logical vector that indicates whether a given relation holds between two corresponding elements in e1 and e2.

Details

All the functions are vectorized over e1 and e2.

stri_cmp_eq tests whether two corresponding strings consist of exactly the same code points, while stri_cmp_neq allow to check whether there is any difference between them. These are locale-independent operations: for natural language text processing, in which the notion of canonical equivalence is more valid, this may not be exactly what you are looking for, see Examples. Also note that stringi always silently removes UTF-8 BOMs from input strings, so e.g. stri_cmp_eq does not take BOMs into account while comparing strings.

On the other hand, stri_cmp_equiv test for canonical equivalence of two strings and is locale-dependent. Additionally, the ICU's Collator may be tuned up so that e.g. the comparison is case-insensitive. To test whether two strings are not canonically equivalent, call stri_cmp_nequiv.

What is more, stri_cmp_le tests whether the elements in the first vector are less than or equal to the corresponding elements in the second vector, stri_cmp_ge whether they are greater or equal, stri_cmp_lt if less, and stri_cmp_gt if greater, see also e.g. %<%< a="">.

Finally, stri_compare is an alias to stri_cmp. They both perform exactly the same locale-dependent operation. Both functions provide a C library's strcmp() look-and-feel, see Value for details.

For more information on ICU's Collator and how to tune it up in stringi, refer to stri_opts_collator. Please note that different locale settings may lead to different results (see the examples below).

See Also

Other locale_sensitive: %!==%, %!=%, %<=%< a="">, %<%< a="">, %===%, %==%, %>=%, %>%, %stri!==%, %stri!=%, %stri<=%< a="">, %stri<%< a="">, %stri===%, %stri==%, %stri>=%, %stri>%; stri_count_coll; stri_detect_coll; stri_duplicated, stri_duplicated_any; stri_enc_detect2; stri_extract_all_coll, stri_extract_first_coll, stri_extract_first_coll, stri_extract_last_coll, stri_extract_last_coll; stri_extract_words; stri_locate_all_coll, stri_locate_first_coll, stri_locate_first_coll, stri_locate_last_coll, stri_locate_last_coll; stri_locate_boundaries; stri_locate_words; stri_opts_collator; stri_order, stri_sort; stri_replace_all_coll, stri_replace_first_coll, stri_replace_first_coll, stri_replace_last_coll, stri_replace_last_coll; stri_split_boundaries; stri_split_coll; stri_trans_tolower, stri_trans_totitle, stri_trans_toupper; stri_unique; stri_wrap; stringi-locale; stringi-search-coll

Examples

if (stri_install_check(silent=TRUE))
# in Polish ch < h:
stri_cmp_lt("hladny", "chladny", stri_opts_collator(locale="pl_PL"))

if (stri_install_check(silent=TRUE))
# in Slovak ch > h:
stri_cmp_lt("hladny", "chladny", stri_opts_collator(locale="sk_SK"))

if (stri_install_check(silent=TRUE))
# < or > (depends on locale):
stri_cmp("hladny", "chladny")

if (stri_install_check(silent=TRUE))
# ignore case differences:
stri_cmp_equiv("hladny", "HLADNY", stri_opts_collator(strength=2))

if (stri_install_check(silent=TRUE))
# alse ignore diacritical differences:
stri_cmp_equiv("hladn\u00FD", "hladny", stri_opts_collator(strength=1, locale="sk_SK"))

if (stri_install_check(silent=TRUE))
# non-normalized vs normalized string:
stri_cmp_equiv(stri_trans_nfkd('\u0105'), '\u105')

if (stri_install_check(silent=TRUE))
# note the difference:
stri_cmp_eq(stri_trans_nfkd('\u0105'), '\u105')

if (stri_install_check(silent=TRUE))
# ligatures:
stri_cmp_equiv("\ufb00", "ff", stri_opts_collator(strength=2))