Greek analyzer

The built-in greek analyzer can be applied to a text field using the following command:

  1. PUT /greek-index
  2. {
  3.   "mappings": {
  4.     "properties": {
  5.       "content": {
  6.         "type": "text",
  7.         "analyzer": "greek"
  8.       }
  9.     }
  10.   }
  11. }

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Stem exclusion

You can use stem_exclusion with this language analyzer using the following command:

  1. PUT index_with_stem_exclusion_greek_analyzer
  2. {
  3.   "settings": {
  4.     "analysis": {
  5.       "analyzer": {
  6.         "stem_exclusion_greek_analyzer": {
  7.           "type": "greek",
  8.           "stem_exclusion": ["αρχή", "έγκριση"]
  9.         }
  10.       }
  11.     }
  12.   }
  13. }

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Greek analyzer internals

The greek analyzer is built using the following components:

  • Tokenizer: standard

  • Token filters:

    • lowercase
    • stop (Greek)
    • keyword
    • stemmer (Greek)

Custom Greek analyzer

You can create a custom Greek analyzer using the following command:

  1. PUT /greek-index
  2. {
  3.   "settings": {
  4.     "analysis": {
  5.       "filter": {
  6.         "greek_stop": {
  7.           "type": "stop",
  8.           "stopwords": "_greek_"
  9.         },
  10.         "greek_stemmer": {
  11.           "type": "stemmer",
  12.           "language": "greek"
  13.         },
  14.         "greek_keywords": {
  15.           "type": "keyword_marker",
  16.           "keywords": []
  17.         }
  18.       },
  19.       "analyzer": {
  20.         "greek_analyzer": {
  21.           "type": "custom",
  22.           "tokenizer": "standard",
  23.           "filter": [
  24.             "lowercase",
  25.             "greek_stop",
  26.             "greek_keywords",
  27.             "greek_stemmer"
  28.           ]
  29.         }
  30.       }
  31.     }
  32.   },
  33.   "mappings": {
  34.     "properties": {
  35.       "content": {
  36.         "type": "text",
  37.         "analyzer": "greek_analyzer"
  38.       }
  39.     }
  40.   }
  41. }

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Generated tokens

Use the following request to examine the tokens generated using the analyzer:

  1. POST /greek-index/_analyze
  2. {
  3.   "field": "content",
  4.   "text": "Οι φοιτητές σπουδάζουν στα ελληνικά πανεπιστήμια. Οι αριθμοί τους είναι 123456."
  5. }

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The response contains the generated tokens:

  1. {
  2.   "tokens": [
  3.     {"token": "φοιτητές","start_offset": 3,"end_offset": 11,"type": "<ALPHANUM>","position": 1},
  4.     {"token": "σπουδάζ","start_offset": 12,"end_offset": 22,"type": "<ALPHANUM>","position": 2},
  5.     {"token": "στα","start_offset": 23,"end_offset": 26,"type": "<ALPHANUM>","position": 3},
  6.     {"token": "ελληνικά","start_offset": 27,"end_offset": 35,"type": "<ALPHANUM>","position": 4},
  7.     {"token": "πανεπιστήμ","start_offset": 36,"end_offset": 48,"type": "<ALPHANUM>","position": 5},
  8.     {"token": "αριθμοί","start_offset": 53,"end_offset": 60,"type": "<ALPHANUM>","position": 7},
  9.     {"token": "τους","start_offset": 61,"end_offset": 65,"type": "<ALPHANUM>","position": 8},
  10.     {"token": "είνα","start_offset": 66,"end_offset": 71,"type": "<ALPHANUM>","position": 9},
  11.     {"token": "123456","start_offset": 72,"end_offset": 78,"type": "<NUM>","position": 10}
  12.   ]
  13. }