Metadata-Version: 2.1
Name: TurkishStemmer
Version: 1.3
Summary: Turkish Stemmer
Home-page: https://github.com/hanefi/turkish-stemmer-python
Author: Hanefi Onaldi
Author-email: abdullahanefi16@gmail.com
License: UNKNOWN
Description: ﻿# Turkish Stemmer for Python
        
        Note : Most of the documentation taken from elasticsearch-analysis-turkishstemmer project. 
        
        Stemmer algorithm for Turkish language.
        
        ## Introduction to Turkish language morphology
        
        > Turkish is an agglutinative language and has a very rich morphological
          stucture. In Turkish, you can form many different words from a single stem by
          appending a sequence of suffixes. For example The word "doktoruymuşsunuz"
          means "You had been the doctor of him". The stem of the word is "doktor" and
          it takes three different suffixes -sU, -ymUş, and -sUnUz.
        
        From "Snowball Description":
        
        > Words are usually composed of a stem and of at least two or three affixes
          appended to it.
        
        > We can analyze noun suffixes in Turkish in two groups. Noun suffixes (eg.
          "doktor-um" meaning "my doctor") and nominal verb suffixes (eg. "doktor-dur"
          meaning ‘is a doctor’). The words ending with nominal verb suffixes can be
          used as verbs in sentences. There are over thirty different suffixes
          classified in these two general groups of suffixes.
        
        > In Turkish, the suffixes are affixed to the stem according to definite
          ordering rules.
        
        From "An affix stripping morphological analyzer for Turkish" paper:
        
        > Turkish has a special place within the natural languages not only being a
          fully concatenative language but also having the suffixes as the only affix
          type. Another feature of the language is that, someone who knows Turkish can
          easily analyze a word even if he/she does not know its stem.
        
        > The phonological rules of Turkish are significant factors that influence
          this feature.
          Ex: (any word)lerim => (any word)-ler-im
          "ler" plural suffix, "im" 1st singular person possessive.
        
        ### Rules
        
        1. The only affix type in Turkish is the suffix.
        
        2. A plural suffix cannot follow a possesive suffix.
        
        3. A suffix in Turkish can have multiple allomorphs in order to provide sound
           harmony in the word to which it is affixed.
        
        4. In Turkish each vowel indicates a distinct syllable.
        
        5. In Turkish, single syllable words are mostly the stem itself
        
        6. If a word has nominal __verb__ suffixes, they always appear at the end of
           the word. They follow __noun__ suffixes or the stem itself at the absence
           of noun suffixes
        
        7. In Turkish, “-lAr” suffix can be used both as a nominal verb suffix (third
           person plural present tense) and as a noun suffix (plural inflection).
        
        8. In Turkish, words do not end with consonants 'b', 'c', 'd', and 'ğ'.
           However, when a suffix starting with a vowel is affixed to a word ending
           with 'p', 'ç', 't' or 'k', the last consonant is transformed into 'b', 'c',
           'd', or 'ğ' respectively. The postlude routine transforms last consonants
           'b', 'c','d', or 'ğ'' back to 'p', 'ç', 't' or 'k', respectively, after
           stemming is complete.
        
        ### Suffix Classes
        
        Class                        | Type
        -----------------------------|----------------
        Nominal verb suffixes        | Inflectional
        Derivational suffixes        | Derivational
        Noun suffixes                | Inflectional
        Tense & person verb suffixes | Inflectional
        Verb suffixes                | Inflectional
        
        ### Suffix allomorphs
        
        Suffix allomorphs are used to create a good sound harmony. They do not change
        the meaning of the word. If a suffix has a capital letter then it has an
        allomorh. If a suffix has a letter in parentheses then it can be omitted.
        Possible allomorphs are given below:
        
        Letter | Allomorph
        -------|------------
        U      | ı,i,u,ü
        C      | c,ç
        A      | a,e
        D      | d,t
        I      | ı,I
        
        ### Nominal Verb Suffixes
        
        a/a | Suffix
        ----|------------------
        1   | –(y)Um
        2   | –sUn
        3   | –(y)Uz
        4   | –sUnUz
        5   | –lAr
        6   | –md
        7   | –n
        8   | –k
        9   | –nUz
        10  | –DUr
        11  | –cAsInA
        12  | –(y)DU
        13  | –(y)sA
        14  | –(y)mUş
        15  | –(y)ken
        
        Suffix transition ordering for nominal verbs can be seen in References[5]
        
        ### Noun Suffixes
        
        a/a | Suffixes
        ----|-------------
        1   | –lAr
        2   | –(U)m
        3   | –(U)mUz
        4   | –(U)n
        5   | –(U)nUz
        6   | –(s)U
        7   | –lArI
        8   | –(y)U
        9   | –nU
        10  | –(n)Un
        11  | –(y)A
        12  | –nA
        13  | –DA
        14  | –nDA
        15  | –DAn
        16  | –nDAn
        17  | –(y)lA
        18  | –ki
        19  | –(n)cA
        
        Suffix transition ordering for nouns can be seen in References[5]
        
        ### Derivational Suffixes
        
        a/a | Suffixes
        ----|----------
        1   | –lUk
        2   | –CU
        3   | –CUk
        4   | –lAş
        5   | –lA
        6   | –lAn
        7   | –CA
        8   | –lU
        9   | –sUz
        
        Initially, we will handle only a small subset of the above suffixes which are
        more common in our domain.
        
        ### Vowel Harmony
        
        This routine checks whether __the last two__ vowels of the word obey vowel
        harmony rules. A brief description of Turkish vowel harmony follows.
        
        Turkish vowel harmony is a two dimensional vowel harmony system, where vowels
        are characterised by two features named frontness and roundness. There are
        vowel harmony rules for each feature.
        
        1. Vowel harmony rule for frontness: Vowels in Turkish are grouped into two
           according to where they are produced. Front produced vowels are formed at
           the front of the mouth ('e', 'i', 'ö', 'ü') and back produced vowels are
           produced nearer to throat ('a', 'ı', 'o', 'u'). According to the vowel
           harmony rule, words cannot contain both front and back vowels. This is one
           of the reasons why suffixes containing vowels can take different forms to
           obey vowel harmony.
        
        2. Vowel harmony rule for roundness: Vowels in Turkish are grouped into two
           according to whether lips are rounded while producing it. 'o', 'ö', 'u' and
           'ü' are rounded vowels whereas 'a', 'e', 'ı' and 'i' are unrounded.
           According to the vowel harmony rules, if the vowel of a syllable is
           unrounded, the following vowel is unrounded as well. If the vowel of a
           syllable is rounded, the following vowels are 'a', 'e', 'u' or 'ü'.
        
        ### Last consonant
        
        Another interesting case in detecting suffixes in Turkish is that, for some
        suffixes, if the word ends with a vowel, a consonant is inserted between the
        rest of the word and the suffix. These merging consonants can be 'y', 'n' or
        's'. When a merging consonant can be inserted before the suffix, the
        representation of the suffix starts with the optional consonant surrounded by
        paranthesis (eg. –(y)Um, -(n)cA). For these kinds of suffixes, if existence of
        a merging consonant is considered, the candidate stem is checked whether it
        ends with a vowel.
        
        If there is no 'y' consonant before the suffix, only the real part of the
        suffix (eg. -Um) is marked for stemming. If there is a 'y' consonant and it is
        preceded by a vowel, 'y' is treated as a merging consonant and both 'y' and
        the candidate suffix (eg. -Um) is marked for stemming. If there is a consonant
        just before 'y', the decision is that the consonant 'y' and the candidate
        suffix are really a part of the stem. In such a case, cursor is not advanced
        to prevent over-stemming. The last case can occur especially when the stem
        originates from another language like in 'lityum' (meaning the element
        Lithium). If the check for vowel harmony was not made, the word would be
        stemmed to 'lit', for '–(y)Um' would be treated as a suffix affixed to it. But
        according to morphological rules of Turkish, the final word would be 'litim',
        not 'lityum' if 'lit' were really the stem of the word and the suffix '–(y)Um'
        were affixed to it. So detecting 'lit' as the stem of the word would be an over
        -stemming.
        
        ### Merging Vowel
        
        Similar to merging consonants, there are merging vowels for some suffixes
        starting with consonants. They can be preceded by merging vowels like in '-(U)
        mUz' suffix when they are affixed to a stem ending with a consonant. In such a
        case, a U vowel ('ı', 'i', 'u' or 'ü' depending on vowel harmony) is inserted
        between the stem and real suffix (e.g. '-mUz') for ease of pronunciation.
        
        ### Some examples
        
        Word / Analysis                | Meaning / Stem
        ------------------------------ |--------------------------------
        Kalelerimizdekilerden          | From the ones at one of our castles
        Kale-lAr-UmUz-DA-ki-lAr-DAn    | Kale
        Çocuğuymuşumcasına             | As if I were her child
        Çocuk-(s)U-(y)mUş-(y)Um-cAsInA | Çocuk
        Kedileriyle                    | With their cats
        Kedi-lAr-(s)U-(y)lA            | Kedi
        Çocuklarımmış                  | Someone told me that they were my children
        çocuk-lAr-(U)m-(y)mUş          | Çocuk
        Kitabımızdı                    | It was our book
        kitap-UmUz-(y)DU               | Kitap
        
        ## Future Work
        
        * Add more verbs suffixes.
        * Add more derivational suffixes.
        
        ## References
        
        1. [Turkish Stemmer used in Lucene](http://snowball.tartarus.org/algorithms/turkish/stemmer.html)
        2. [Java Implementation](http://snowball.tartarus.org/archives/snowball-discuss/att-0875/02-TurkishStemmer.java)
        3. [Snowball Implementation](http://snowball.tartarus.org/algorithms/turkish/stem_Unicode.sbl)
        4. [Snowball Description](http://snowball.tartarus.org/algorithms/turkish/accompanying_paper.doc)
        5. [An affix stripping morphological analyzer for Turkish](http://web.itu.edu.tr/~gulsenc/papers/iasted.pdf)
        6. [Lead Generation](https://en.wikipedia.org/wiki/Lead_generation)
        7. [Vowel Harmony](https://en.wikipedia.org/wiki/Vowel_harmony#Turkish)
        8. [Turkish Suffixes](https://en.wiktionary.org/wiki/Appendix:Turkish_suffixes)
        9. [Turkish Grammar](https://en.wikipedia.org/wiki/Turkish_grammar)
        10. [Turkish Language](https://en.wikipedia.org/wiki/Turkish_language)
        11. [Tartarus](http://tartarus.org/)
        12. [Information Retrieval on Turkish Texts](http://www.users.muohio.edu/canf/papers/JASIST2008offPrint.pdf)
        
        ## Installation
        
        Copy the module folder inside PythonXX/Lib/site-packages or inside your application directory.
        
        ## Usage
        ```python
        >>> from TurkishStemmer import TurkishStemmer
        >>> stemmer = TurkishStemmer()
        >>> stemmer.stem("okuldakilerden")
        okul
        ```
        
        ## Contributing
        
        1. Fork it ( `http://github.com/<my-github-username>/turkishstemmer-python/fork` )
        2. Create your feature branch (`git checkout -b my-new-feature`)
        3. Commit your changes (`git commit -am 'Add some feature'`)
        4. Push to the branch (`git push origin my-new-feature`)
        5. Create new Pull Request
        
        ## License
        
        turkishstemmer-python is licensed under the Apache Software License, Version 2.0.
        
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