[jira] [Created] (OPENNLP-1330) Parser top k parses doesn't show "top" (highest probability) parses.

["Eric Ihli (Jira)" <ji...@apache.org>]

Eric Ihli created OPENNLP-1330:
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             Summary: Parser top k parses doesn't show "top" (highest probability) parses.
                 Key: OPENNLP-1330
                 URL: https://issues.apache.org/jira/browse/OPENNLP-1330
             Project: OpenNLP
          Issue Type: Bug
          Components: Parser
    Affects Versions: 1.9.4
            Reporter: Eric Ihli
         Attachments: FixParserTopK.patch

 The default "top n parses" of 1 shows the most likely parse; one with a log prob of -2.9.

Passing in anything greater than 1 returns the least probable parses.
{code:java}
➜ bin git:(master) echo "Eric is testing." | ./opennlp Parser -k 1 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.515s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))

Average: 41.7 sent/s
Total: 1 sent
Runtime: 0.024s
Execution time: 2.585 seconds
➜ bin git:(master) echo "Eric is testing." | ./opennlp Parser -k 2 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.578s)
0 -14.968552218782305 (TOP (S (NP (NNP Eric)) (SBAR (S (ADVP (VBZ is)) (VBG testing.)))))
1 -13.957766393572408 (TOP (S (SBAR (S (NP (NNP Eric)) (ADVP (VBZ is)))) (VBG testing.)))

Average: 95.2 sent/s
Total: 2 sent
Runtime: 0.021s
Execution time: 2.640 seconds

{code}
 The fix is clear and simple. We should be taking from the first of the TreeSet rather than from the end.
{code:java}

 else if (numParses == 1) {
 return new Parse[] {completeParses.first()};
 }
 else {
 List<Parse> topParses = new ArrayList<>(numParses);
 while (!completeParses.isEmpty() && topParses.size() < numParses) {
 Parse tp = completeParses.last();      //// <--- Change to .first()
 completeParses.remove(tp);
 topParses.add(tp);
 //parses.remove(tp);
 }
 return topParses.toArray(new Parse[topParses.size()]);
 }{code}
After patch, results are what I expect.

 
{code:java}
➜ bin git:(master) ✗ echo "Eric is testing." | ./opennlp Parser -k 1 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.517s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))

Average: 45.5 sent/s
Total: 1 sent
Runtime: 0.022s
Execution time: 2.580 seconds
➜ bin git:(master) ✗ echo "Eric is testing." | ./opennlp Parser -k 2 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.530s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))
1 -3.1132674983145825 (TOP (S (NP (NNP Eric)) (VP (VBZ is) (NP (NN testing.)))))

Average: 90.9 sent/s
Total: 2 sent
Runtime: 0.022s
Execution time: 2.596 seconds
{code}
 



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