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From "Adrien Grand (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-3475) ShingleFilter should handle positionIncrement of zero, e.g. synonyms
Date Mon, 29 Jan 2018 08:39:00 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-3475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16343073#comment-16343073
] 

Adrien Grand commented on LUCENE-3475:
--------------------------------------

I'm not going to work on this in the short term but I just wrote a test case in case someone
else has interest in fixing this issue:

{code}
  public void testSynonyms1() throws IOException {
    Token t1 = new Token("small", 0, 5);
    Token t2 = new Token("little", 0, 5);
    t2.setPositionIncrement(0);
    Token t3 = new Token("thing", 6, 11);
    TokenStream tk = new CannedTokenStream(t1, t2, t3);
    ShingleFilter f = new ShingleFilter(tk, 2, 2);
    f.setOutputUnigrams(false);
    assertTokenStreamContents(f,
        new String[] { "small thing", "little thing" },
        new int[] {0, 0},
        new int[] {11, 11},
        new int[] {1, 0});
  }

  public void testSynonyms2() throws IOException {
    Token t1 = new Token("small", 0, 5);
    Token t2 = new Token("thing", 6, 11);
    Token t3 = new Token("object", 6, 11);
    t3.setPositionIncrement(0);
    TokenStream tk = new CannedTokenStream(t1, t2, t3);
    ShingleFilter f = new ShingleFilter(tk, 2, 2);
    f.setOutputUnigrams(false);
    assertTokenStreamContents(f,
        new String[] { "small thing", "small object" },
        new int[] {0, 0},
        new int[] {11, 11},
        new int[] {1, 0});
  }
{code}

> ShingleFilter should handle positionIncrement of zero, e.g. synonyms
> --------------------------------------------------------------------
>
>                 Key: LUCENE-3475
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3475
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: modules/analysis
>    Affects Versions: 3.4
>            Reporter: Cameron
>            Priority: Minor
>              Labels: newdev
>
> ShingleFilter is creating shingles for a single term that has been expanded by synonyms
when it shouldn't. The position increment is 0.
> As an example, I have an Analyzer with a SynonymFilter followed by a ShingleFilter. Assuming
car and auto are synonyms, the SynonymFilter produces two tokens and position 1: car, auto.
The ShingleFilter is then producing 3 tokens, when there should only be two: car, car auto,
auto. This behavior seems incorrect.



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