Thanks Erik, Hoss -
I will try MultiPhraseQuery and report back.
Back in an email thread with Doug be mentioned SpanQuery would work, and
in a fashion it does, but I can't differentiate between terms at the
same position and contiguous positions. The problem gets worse if I
want to test for more than two terms at the same position ( moon / noun
/ end_of_sentence / ...), which opens it up to wider contiguous spaces.
Would it make sense to extend SpanNearQuery for this case, perhaps with
a slop of a special value (-1) to indicate terms should be found at the
same position? I'm not sure how difficult this would be to represent in
the underlying queues keeping track of matches.
---Marc
Erik Hatcher wrote:
Marc,
SpanNearQuery isn't capable of performing the proximity to within
only a single position in the manner you've described. A slop of 0
means the terms must be contiguous with no gaps, which also allows
for matches in the same position as in your first example.
I think MultiPhraseQuery (from svn trunk) will do what you want
though. Please try that and report back on how it works for you.
Erik
: i have a problem with a SpanNearQuery returning incorrect (false
: positive) results.
I'm not familiar with how Span queries are implimented, but there doesn't
appear to be any test cases dealing with an index where term position
increments are ever 0, so i can neither confirm nor deny the bug you're
seeing.
Can you post code demonstrating the problem? ideally in the form of
a simple, self contained, JUnit test?
-Hoss
On Jan 4, 2006, at 9:39 PM, Marc Hadfield wrote:
hello all -
i have a problem with a SpanNearQuery returning incorrect (false
positive) results.
I am creating the context of a field using tokens which have
position increment set to either 1 or 0. The position increment is
set to 0 for special tokens, in this case part-of-speech markers.
Thus, brackets set of position increments:
[The __pos_dt] [cow __pos_noun] [jumped __pos_verb] [over
__pos_prep] [the __pos_dt] [moon __pos_noun] [. __pos_.]
My Span Query looks like:
SpanQuery sq = new SpanNearQuery(new SpanQuery[]
{
new SpanTermQuery(new Term("content",
"jumped")),
new SpanTermQuery(new
Term("content", "__pos_verb"))
}, 0, false);
This correctly finds the span: [jumped __pos_verb]
However, if I query:
SpanQuery sq = new SpanNearQuery(new SpanQuery[]
{
new SpanTermQuery(new Term("content",
"jumped")),
new SpanTermQuery(new
Term("content", "__pos_noun"))
}, 0, false);
This incorrectly finds the span: [cow __pos_noun] [jumped __pos_verb]
This is wrong because there is a distance of 1 between the tokens,
not 0.
I am using a recent version of Lucene from SVN.
I am thinking that the problem is related to the position increment
being set to 0 for the first token of the incorrect "match" -- thus
perhaps this is a bug in the SpanNearQuery?
Best,
Marc
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