Elbek Kamoliddinov created LUCENE-9100:
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Summary: JapaneseTokenizer produces inconsistent tokens
Key: LUCENE-9100
URL: https://issues.apache.org/jira/browse/LUCENE-9100
Project: Lucene - Core
Issue Type: Bug
Components: modules/analysis
Affects Versions: 7.2
Reporter: Elbek Kamoliddinov
We use {{JapaneseTokenizer}} on prod and seeing some inconsistent behavior.
With this text:
{{"マギアリス【単版話】 4話 (Unlimited Comics)"}} I get different results if I insert
space before `【` char. Here is the small code snippet demonstrating the case
(not we use our own dictionary and connection costs):
{code:java}
Analyzer analyzer = new Analyzer() {
@Override
protected TokenStreamComponents createComponents(String fieldName) {
// Tokenizer tokenizer = new
JapaneseTokenizer(newAttributeFactory(), null, true,
JapaneseTokenizer.Mode.SEARCH);
Tokenizer tokenizer = new
JapaneseTokenizer(newAttributeFactory(), dictionaries.systemDictionary,
dictionaries.unknownDictionary, dictionaries.connectionCosts, null, true,
JapaneseTokenizer.Mode.SEARCH);
return new TokenStreamComponents(tokenizer, new
LowerCaseFilter(tokenizer));
}
};
String text1 = "マギアリス【単版話】 4話 (Unlimited Comics)";
String text2 = "マギアリス 【単版話】 4話 (Unlimited Comics)"; //inserted space
try (TokenStream tokens = analyzer.tokenStream("field", new
StringReader(text1))) {
CharTermAttribute chars =
tokens.addAttribute(CharTermAttribute.class);
tokens.reset();
while (tokens.incrementToken()) {
System.out.println(chars.toString());
}
tokens.end();
} catch (IOException e) {
// should never happen with a StringReader
throw new RuntimeException(e);
} {code}
Output is:
{code:java}
//text1
マギ
アリス
単
版
話
4
話
unlimited
comics
//text2
マギア
リス
単
版
話
4
話
unlimited
comics{code}
It looks like tokenizer doesn't view the punctuation (\{{【}} is
\{{Character.START_PUNCTUATION}} type) as an indicator that there should be a
token break, and somehow 【 punctuation char causes difference in the output.
If I use the {{JapaneseTokenizer}} tokenizer then this problem doesn't manifest
because it doesn't tokenize {{マギアリス}} into multiple tokens and outputs as is.
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