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prefilter bad results before adding details and reranking

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Move the first cutting of the result list before reranking
by result match. This means that results with significantly
less importance are removed early and independently of the
fact how well they match the original query.

Fixes #3266.
This commit is contained in:
Sarah Hoffmann 2024-02-06 20:29:48 +01:00
parent 2833362cf6
commit 4ce13f5c1f
1 changed files with 15 additions and 5 deletions
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20
nominatim/api/search/geocoder.py
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@ -104,19 +104,27 @@ class ForwardGeocoder:
return SearchResults(results.values())
def pre_filter_results(self, results: SearchResults) -> SearchResults:
""" Remove results that are significantly worse than the
best match.
"""
if results:
max_ranking = min(r.ranking for r in results) + 0.5
results = SearchResults(r for r in results if r.ranking < max_ranking)
return results
def sort_and_cut_results(self, results: SearchResults) -> SearchResults:
""" Remove badly matching results, sort by ranking and
limit to the configured number of results.
"""
if results:
min_ranking = min(r.ranking for r in results)
results = SearchResults(r for r in results if r.ranking < min_ranking + 0.5)
results.sort(key=lambda r: r.ranking)
if results:
min_rank = results[0].rank_search
min_ranking = results[0].ranking
results = SearchResults(r for r in results
if r.ranking + 0.05 * (r.rank_search - min_rank)
if r.ranking + 0.03 * (r.rank_search - min_rank)
< min_ranking + 0.5)
results = SearchResults(results[:self.limit])
@ -174,6 +182,7 @@ class ForwardGeocoder:
if query:
searches = [wrap_near_search(categories, s) for s in searches[:50]]
results = await self.execute_searches(query, searches)
results = self.pre_filter_results(results)
await add_result_details(self.conn, results, self.params)
log().result_dump('Preliminary Results', ((r.accuracy, r) for r in results))
results = self.sort_and_cut_results(results)
@ -203,6 +212,7 @@ class ForwardGeocoder:
if searches:
# Execute SQL until an appropriate result is found.
results = await self.execute_searches(query, searches[:50])
results = self.pre_filter_results(results)
await add_result_details(self.conn, results, self.params)
log().result_dump('Preliminary Results', ((r.accuracy, r) for r in results))
self.rerank_by_query(query, results)