Portuguese stemming algorithm

Links to resources

Snowball main page

The stemmer in Snowball

The ANSI C stemmer

— and its header

Sample Portuguese vocabulary

Its stemmed equivalent

Vocabulary + stemmed equivalent in two columns

Tar-gzipped file of all of the above

Portuguese stop word list

The stemmer in Snowball — MS DOS Latin I encodings

Romance language stemmers

word

stem

word

stem

boa boainain boas bôas boassu boataria boate boates boatos bob boba bobagem bobagens bobalhões bobear bobeira bobinho bobinhos bobo bobs boca bocadas bocadinho bocado bocaiúva boçal bocarra bocas bode bodoque body boeing boem boemia boêmio boêmios bogotá boi bóia boiando

=>

boa boainain boas bôas boassu boat boat boat boat bob bob bobag bobagens bobalhõ bob bobeir bobinh bobinh bob bobs boc boc bocadinh boc bocaiúv boçal bocarr boc bod bodoqu body boeing boem boem boêmi boêmi bogot boi bói boi

quiabo quicaram quickly quieto quietos quilate quilates quilinhos quilo quilombo quilométricas quilométricos quilômetro quilômetros quilos química químicas químico químicos quimioterapia quimioterápicos quimono quincas quinhão quinhentos quinn quino quinta quintal quintana quintanilha quintão quintessência quintino quinto quintos quintuplicou quinze quinzena quiosque

=>

quiab quic quickly quiet quiet quilat quilat quilinh quil quilomb quilométr quilométr quilômetr quilômetr quil químic químic químic químic quimioterap quimioteráp quimon quinc quinhã quinhent quinn quin quint quintal quintan quintanilh quintã quintessent quintin quint quint quintuplic quinz quinzen quiosqu

The stemming algorithm

á   é   í   ó   ú   â   ê   ô   ç   ã   õ   ü   ñ

a   e   i   o   u   á   é   í   ó   ú   â   ê   ô

ã   õ

Search for the longest among the following suffixes, and perform the action indicated.

eza   ezas   ico   ica   icos   icas   ismo   ismos   ável   ível   ista   istas   oso   osa   osos   osas   amento   amentos   imento   imentos   adora   ador   aça~o   adoras   adores   aço~es   ante   antes   ância

delete if in R2

logía   logías

replace with log if in R2

ución   uciones

replace with u if in R2

ência   ências

replace with ente if in R2

amente

delete if in R1

if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,

if preceded by os, ic or ad, delete if in R2

mente

delete if in R2

if preceded by ante, avel or ível, delete if in R2

idade   idades

delete if in R2

if preceded by abil, ic or iv, delete if in R2

iva   ivo   ivas   ivos

delete if in R2

if preceded by at, delete if in R2

ira   iras

replace with ir if in RV and preceded by e

Search for the longest among the following suffixes in RV, and if found, delete.

ada   ida   ia   aria   eria   iria   ará   ara   erá   era   irá   ava   asse   esse   isse   aste   este   iste   ei   arei   erei   irei   am   iam   ariam   eriam   iriam   aram   eram   iram   avam   em   arem   erem   irem   assem   essem   issem   ado   ido   ando   endo   indo   ara~o   era~o   ira~o   ar   er   ir   as   adas   idas   ias   arias   erias   irias   arás   aras   erás   eras   irás   avas   es   ardes   erdes   irdes   ares   eres   ires   asses   esses   isses   astes   estes   istes   is   ais   eis   íeis   aríeis   eríeis   iríeis   áreis   areis   éreis   ereis   íreis   ireis   ásseis   ésseis   ísseis   áveis   ados   idos   ámos   amos   íamos   aríamos   eríamos   iríamos   áramos   éramos   íramos   ávamos   emos   aremos   eremos   iremos   ássemos   êssemos   íssemos   imos   armos   ermos   irmos   eu   iu   ou   ira   iras

If the last step to be obeyed — either step 1 or 2 — altered the word, do step 3

Delete suffix i if in RV and preceded by c

If the word ends with one of the suffixes

os   a   i   o   á   í   ó

in RV, delete it

If the word ends with one of

e   é   ê

in RV, delete it, and if preceded by gu (or ci) with the u (or i) in RV, delete the u (or i).

Or if the word ends ç remove the cedilla

Turn a~, o~ back into ã, õ

The same algorithm in Snowball

routines (
           prelude postlude mark_regions
           RV R1 R2
           standard_suffix
           verb_suffix
           residual_suffix
           residual_form
)

externals ( stem )

integers ( pV p1 p2 )

groupings ( v )

stringescapes {}

/* special characters (in ISO Latin I) */

stringdef a'   hex 'E1'  // a-acute
stringdef a^   hex 'E2'  // a-circumflex e.g. 'bota^nico
stringdef e'   hex 'E9'  // e-acute
stringdef e^   hex 'EA'  // e-circumflex
stringdef i'   hex 'ED'  // i-acute
stringdef o^   hex 'F4'  // o-circumflex
stringdef o'   hex 'F3'  // o-acute
stringdef u'   hex 'FA'  // u-acute
stringdef c,   hex 'E7'  // c-cedilla

stringdef a~   hex 'E3'  // a-tilde
stringdef o~   hex 'F5'  // o-tilde


define v 'aeiou{a'}{e'}{i'}{o'}{u'}{a^}{e^}{o^}'

define prelude as repeat (
    [substring] among(
        '{a~}' (<- 'a~')
        '{o~}' (<- 'o~')
        ''     (next)
    ) //or next
)

define mark_regions as (

    $pV = limit
    $p1 = limit
    $p2 = limit  // defaults

    do (
        ( v (non-v gopast v) or (v gopast non-v) )
        or
        ( non-v (non-v gopast v) or (v next) )
        setmark pV
    )
    do (
        gopast v gopast non-v setmark p1
        gopast v gopast non-v setmark p2
    )
)

define postlude as repeat (
    [substring] among(
        'a~' (<- '{a~}')
        'o~' (<- '{o~}')
        ''   (next)
    ) //or next
)

backwardmode (

    define RV as $pV <= cursor
    define R1 as $p1 <= cursor
    define R2 as $p2 <= cursor

    define standard_suffix as (
        [substring] among(

            'eza' 'ezas'
            'ico' 'ica' 'icos' 'icas'
            'ismo' 'ismos'
            '{a'}vel'
            '{i'}vel'
            'ista' 'istas'
            'oso' 'osa' 'osos' 'osas'
            'amento' 'amentos'
            'imento' 'imentos'

           'adora' 'ador' 'a{c,}a~o'
           'adoras' 'adores' 'a{c,}o~es'  // no -ic test
           'ante' 'antes' '{a^}ncia' // Note 1
            (
                R2 delete
            )
            'log{i'}a'
            'log{i'}as'
            (
                R2 <- 'log'
            )
            'uci{o'}n' 'uciones'
            (
                R2 <- 'u'
            )
            '{e^}ncia' '{e^}ncias'
            (
                R2 <- 'ente'
            )
            'amente'
            (
                R1 delete
                try (
                    [substring] R2 delete among(
                        'iv' (['at'] R2 delete)
                        'os'
                        'ic'
                        'ad'
                    )
                )
            )
            'mente'
            (
                R2 delete
                try (
                    [substring] among(
                        'ante' // Note 1
                        'avel'
                        '{i'}vel' (R2 delete)
                    )
                )
            )
            'idade'
            'idades'
            (
                R2 delete
                try (
                    [substring] among(
                        'abil'
                        'ic'
                        'iv'   (R2 delete)
                    )
                )
            )
            'iva' 'ivo'
            'ivas' 'ivos'
            (
                R2 delete
                try (
                    ['at'] R2 delete // but not a further   ['ic'] R2 delete
                )
            )
            'ira' 'iras'
            (
                RV 'e'  // -eira -eiras usually non-verbal
                <- 'ir'
            )
        )
    )

    define verb_suffix as setlimit tomark pV for (
        [substring] among(
            'ada' 'ida' 'ia' 'aria' 'eria' 'iria' 'ar{a'}' 'ara' 'er{a'}'
            'era' 'ir{a'}' 'ava' 'asse' 'esse' 'isse' 'aste' 'este' 'iste'
            'ei' 'arei' 'erei' 'irei' 'am' 'iam' 'ariam' 'eriam' 'iriam'
            'aram' 'eram' 'iram' 'avam' 'em' 'arem' 'erem' 'irem' 'assem'
            'essem' 'issem' 'ado' 'ido' 'ando' 'endo' 'indo' 'ara~o'
            'era~o' 'ira~o' 'ar' 'er' 'ir' 'as' 'adas' 'idas' 'ias'
            'arias' 'erias' 'irias' 'ar{a'}s' 'aras' 'er{a'}s' 'eras'
            'ir{a'}s' 'avas' 'es' 'ardes' 'erdes' 'irdes' 'ares' 'eres'
            'ires' 'asses' 'esses' 'isses' 'astes' 'estes' 'istes' 'is'
            'ais' 'eis' '{i'}eis' 'ar{i'}eis' 'er{i'}eis' 'ir{i'}eis'
            '{a'}reis' 'areis' '{e'}reis' 'ereis' '{i'}reis' 'ireis'
            '{a'}sseis' '{e'}sseis' '{i'}sseis' '{a'}veis' 'ados' 'idos'
            '{a'}mos' 'amos' '{i'}amos' 'ar{i'}amos' 'er{i'}amos'
            'ir{i'}amos' '{a'}ramos' '{e'}ramos' '{i'}ramos' '{a'}vamos'
            'emos' 'aremos' 'eremos' 'iremos' '{a'}ssemos' '{e^}ssemos'
            '{i'}ssemos' 'imos' 'armos' 'ermos' 'irmos' 'eu' 'iu' 'ou'

            'ira' 'iras'
                (delete)
        )
    )

    define residual_suffix as (
        [substring] among(
            'os'
            'a' 'i' 'o' '{a'}' '{i'}' '{o'}'
                ( RV delete )
        )
    )

    define residual_form as (
        [substring] among(
            'e' '{e'}' '{e^}'
                ( RV delete [('u'] test 'g') or
                             ('i'] test 'c') RV delete )
            '{c,}' (<-'c')
        )
    )
)

define stem as (
    do prelude
    do mark_regions
    backwards (
        do (
            ( ( standard_suffix or verb_suffix )
              and do ( ['i'] test 'c' RV delete )
            )
            or residual_suffix
        )
        do residual_form
    )
    do postlude
)

/*
    Note 1: additions of 15 Jun 2005
*/