Capitularia Lucene Tools

This project contains:

• a stemmer for the Latin language,
• a filter that converts roman numerals into arabic ones, and
• a value source that correctly sorts strings with numbers.

Latin Stem Filter

Usage example in conf/schema.xml:

<fieldType name="text_la_stem" class="solr.TextField" positionIncrementGap="100">
    <analyzer>
        <tokenizer class="solr.StandardTokenizerFactory"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="de.uni_koeln.capitularia.lucene_tools.LatinStemFilterFactory"
                preserveOriginal="true" minNounSize="3" minVerbSize="3"/>
    </analyzer>
</fieldType>

The stemmer uses an algorithm by Schinke et al.

See:

Schinke R, Greengrass M, Robertson AM and Willett P (1996) A stemming algorithm for Latin text databases. Journal of Documentation, 52: 172-187.

https://snowballstem.org/otherapps/schinke/

Roman Numerals Filter

The filter will convert roman XLII to arabic 42.

Usage example in conf/schema.xml:

<fieldType name="text_la_stem" class="solr.TextField" positionIncrementGap="100">
    <analyzer>
        <tokenizer class="solr.StandardTokenizerFactory"/>
        <filter class="solr.LowerCaseFilterFactory"/>
        <filter class="de.uni_koeln.capitularia.lucene_tools.RomanNumeralsFilterFactory"
                preserveOriginal="true"/>
    </analyzer>
</fieldType>

Sorting Value Source

The value source generates strings that sort correctly when used as keys, like this:

1. paris-bn-lat-4638
2. paris-bn-lat-10528

instead of alphabetically, like this:

1. paris-bn-lat-10528
2. paris-bn-lat-4638

Usage example in conf/solrconfig.xml:

<config>
    <valueSourceParser
        name="strnumsort"
        class="de.uni_koeln.capitularia.lucene_tools.StringNumberSortValueSourceParser"
    />
    ...
</config>

In the query set the sort parameter to: strnumsort(my_alphanum_id) asc