remotes::install_gitlab("hrbrmstr/pluralize")
# or
remotes::install_github("hrbrmstr/pluralize")

library(pluralize)

# current version
packageVersion("pluralize")
## [1] '0.2.0'

pluralize('test')
## [1] "tests"

singularize('test')
## [1] "test"

singularize(c("boats", "houses", "cats", "rivers"))
## [1] "boat"  "house" "cat"   "river"

pluralize(singularize(c("boats", "houses", "cats", "rivers")))
## [1] "boats"  "houses" "cats"   "rivers"

singularize(c("buses", "wishes", "pitches", "boxexs"))
## [1] "bus"   "wish"  "pitch" "boxex"

pluralize(singularize(c("buses", "wishes", "pitches", "boxexs")))
## [1] "buses"   "wishes"  "pitches" "boxexes"

singularize(c("pennies", "spies", "babies", "cities", "daisies"))
## [1] "penny"  "spy"    "baby"   "city"   "daisie"

pluralize(singularize(c("pennies", "spies", "babies", "cities", "daisies")))
## [1] "pennies" "spies"   "babies"  "cities"  "daisies"

singularize(c("sheep", "fish", "deer", "species", "aircraft"))
## [1] "sheep"    "fish"     "deer"     "specie"   "aircraft"

pluralize(singularize(c("sheep", "fish", "deer", "species", "aircraft")))
## [1] "sheep"    "fish"     "deer"     "species"  "aircraft"

pluralize('test', 5)
## [1] "tests"

pluralize('test', 5, TRUE)
## [1] "5 tests"

pluralize('regex')
## [1] "regexes"

add_plural_rule("gex", "gexii")

pluralize('regex')
## [1] "regexii"

singularize('singles')
## [1] "single"

add_singular_rule("singles", "singular")

singularize('singles')
## [1] "singular"

pluralize("irregular")
## [1] "irregulars"

pluralize(c("woman", "man", "child", "tooth", "foot", "person", "leaf"))
## [1] "women"    "men"      "children" "teeth"    "feet"     "people"   "leaves"

singularize(c("woman", "man", "child", "tooth", "foot", "person", "leaf"))
## [1] "woman"  "man"    "child"  "tooth"  "foot"   "person" "leaf"

add_irregular_rule("irregular", "regular")

pluralize("irregular")
## [1] "regular"

pluralize("paper")
## [1] "papers"

add_uncountable_rule("paper")

pluralize("paper")
## [1] "paper"