Home > Class Reference > %SYS namespace > %iKnow.Stemmer


This class represents an object responsible for stemming user input into a base form, either through some internal algorithm or through an external library. Use GetDefault() to instantiate the default stemmer for a particular language or GetCustom() to retrieve one configured with custom settings saved as a %iKnow.Stemming.Configuration object.

See also %iKnow.Stemming.Utils for defining exception rules.

Property Inventory (Including Private)

Method Inventory (Including Private)

Properties (Including Private)

property DecompoundProps [ Private , MultiDimensional ];
Property methods: DecompoundPropsDisplayToLogical(), DecompoundPropsGet(), DecompoundPropsIsValid(), DecompoundPropsLogicalToDisplay(), DecompoundPropsLogicalToOdbc(), DecompoundPropsNormalize(), DecompoundPropsSet()
property DefaultLanguage as %String;
The default language to use when calling any Stem() method without supplying a language explicitly.
Property methods: DefaultLanguageDisplayToLogical(), DefaultLanguageGet(), DefaultLanguageIsValid(), DefaultLanguageLogicalToDisplay(), DefaultLanguageLogicalToOdbc(), DefaultLanguageNormalize(), DefaultLanguageSet()

Methods (Including Private)

method Decompound(pWord As %String, Output pCompounds, pLanguage As %String = "", pStemCompounds As %Boolean = 1) as %Status [ Language = objectscript ]

This method will try to decompound the supplied pWord into composing elements and returns the stems of those elements:

pCompounds(n) = $lb([stem], [start pos in string], [score])

Note that most punctuation encountered in pWord (including spaces) will be considered as explicit compound boundaries (like hyphens).

See also %iKnow.Stemming.DecompoundUtils.

final classmethod GetByDomain(pDomainId As %Integer, Output pStemmer As %iKnow.Stemmer) as %Status [ Language = objectscript ]
Returns the stemmer configured according to the domain settings of the specified domain.
final classmethod GetCustom(pConfigName As %String, Output pStemmer As %iKnow.Stemmer) as %Status [ Language = objectscript ]
Instantiates a custom stemmer object based on the stemmer configuration named pConfigName. See also %iKnow.Stemming.Configuration.
final classmethod GetDefault(pLanguage As %String, Output pStemmer As %iKnow.Stemmer) as %Status [ Language = objectscript ]

Returns the default stemmer object for language pLanguage, which is resolved as follows:

  1. Check if there is a pLanguage*.aff file in INSTALL_DIR/dev/hunspell/ and just use the first you come across for the requested language, instantiating a hunspell-based stemmer object. Most libraries have a more detailed locale such as en_US.aff, which is covered by this check. Note that pLanguage should refer to the two-letter ISO code for that language.
  2. If no such file is found, check if there is a directory called INSTALL_DIR/dev/hunspell/pLanguage with a *.aff file within. If found, use it to instantiate a hunspell-based stemmer object.
  3. If no hunspell library is found, try to check if a %Text.Text implementation corresponding to the requested language is found and use its Standardize() method (through a %iKnow.Stemming.TextStemmer instance)
  4. If none found, revert to the default in %Text.Text:Standardize(), which will mostly just lowercase the string.
method Reload() as %Status [ Language = objectscript ]
Resets any properties, rules or other cached information this object was using
method Stem(pString As %String, pLanguage As %String = "", pLexType As %Integer = $$$ENTTYPECONCEPT) as %String [ Language = objectscript ]
This method will return the fully stemmed version of any string (1 or more words). If the stemmed version is equal to the original string, it will return the empty string.
final method StemAny(pString As %String, pLanguage As %String = "", pLexType As %Integer = $$$ENTTYPECONCEPT) as %String [ Language = objectscript ]
This convenience method will return the fully stemmed version of any string (1 or more words). This method will return a nonempty value, regardless of whether a stemmed version was found or whether it consists of more than one word.

Inherited Members

Inherited Methods (Including Private)