From 37434f5baf632e839dc14b3c7d8745287cb9368a Mon Sep 17 00:00:00 2001
From: Douglas Rumbaugh <dbr4@psu.edu>
Date: Tue, 25 Jul 2023 11:17:36 -0400
Subject: Benchmarks: mtree and vptree benchmark updates

Note: cosine similarity doesn't seem to work for VPTree--I don't think
that it is actually a metric, upon further research. At the very least I
can't find anyone claiming it is, and I've found several people claiming
it isn't. On testing with the Word2Vec data, Euclidean distance works
insofar as the M-Tree and VPTree return the same KNN results for test
queries, whereas Cosine Similarity does not work.
---
 benchmarks/include/bench_utility.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

(limited to 'benchmarks/include/bench_utility.h')

diff --git a/benchmarks/include/bench_utility.h b/benchmarks/include/bench_utility.h
index 6610ab4..28040be 100644
--- a/benchmarks/include/bench_utility.h
+++ b/benchmarks/include/bench_utility.h
@@ -40,7 +40,7 @@ typedef de::WeightedRecord<key_type, value_type, weight_type> WRec;
 typedef de::Record<key_type, value_type> Rec;
 
 const size_t W2V_SIZE = 300;
-typedef de::CosinePoint<double, W2V_SIZE> Word2VecRec;
+typedef de::EuclidPoint<double, W2V_SIZE> Word2VecRec;
 
 typedef de::DynamicExtension<WRec, de::WSS<WRec>, de::WSSQuery<WRec>> ExtendedWSS;
 typedef de::DynamicExtension<Rec, de::TrieSpline<Rec>, de::TrieSplineRangeQuery<Rec>> ExtendedTSRQ;
@@ -68,6 +68,17 @@ struct btree_key_extract {
     }
 };
 
+struct euclidean_distance {
+    double operator()(const Word2VecRec &first, const Word2VecRec &second) const {
+        double dist = 0;
+        for (size_t i=0; i<W2V_SIZE; i++) {
+            dist += (first.data[i] - second.data[i]) * (first.data[i] - second.data[i]);
+        }
+        
+        return std::sqrt(dist);
+    }
+};
+
 
 struct cosine_similarity {
     double operator()(const Word2VecRec &first, const Word2VecRec &second) const {
@@ -86,7 +97,7 @@ struct cosine_similarity {
 };
 
 typedef tlx::BTree<key_type, btree_record, btree_key_extract> TreeMap;
-typedef mt::mtree<Word2VecRec, cosine_similarity> MTree;
+typedef mt::mtree<Word2VecRec, euclidean_distance> MTree;
 
 static gsl_rng *g_rng;
 static std::set<WRec> *g_to_delete;
-- 
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