search/embeddings: speed up similarity search by more than 50%

Exploit normalization of embeddings. Document this assumption and fulfill it in the mock embedding model.

packages/SemanticText.package/OpenAIEmbeddingModel.class/instance/getEmbeddingsForAll.config..st

@@ -1,6 +1,6 @@
 service
 getEmbeddingsForAll: strings config: aConfigOrNil
-	"Answer a collection with one embedding for each string. Each embedding vector is a Float32Array of numbers."
+	"Answer a collection with one embedding for each string. Each embedding vector is a Float32Array of numbers. Each vector is normalized, i.e., has a length very close to 1."
 
 	| embeddingResult |
 	embeddingResult := self

packages/SemanticText.package/OpenAIEmbeddingModel.class/methodProperties.json

@@ -12,7 +12,7 @@
 		"getEmbeddingFor:" : "ct 8/20/2023 12:49",
 		"getEmbeddingFor:config:" : "ct 8/20/2023 13:03",
 		"getEmbeddingsForAll:" : "ct 8/20/2023 22:55",
-		"getEmbeddingsForAll:config:" : "ct 8/20/2023 19:43",
+		"getEmbeddingsForAll:config:" : "ct 8/29/2023 17:16",
 		"name:" : "ct 8/19/2023 22:15",
 		"pathToEndpoint" : "ct 8/17/2023 18:07",
 		"priceFor:" : "ct 8/27/2023 16:55",

packages/SemanticText.package/SemanticCorpus.class/instance/distanceBetween.and..st

@@ -1,21 +1,7 @@
 private
 distanceBetween: embedding and: anotherEmbedding
-	"cosine distance"
+	"Answer the cosine distance between both embeddings. The length of embeddings is ignored, so senders have to take care not to compare differences between pairs of vectors with different total scalars."
 
-	| abs otherAbs |
 	anotherEmbedding ifNil: [^ Float infinity].
 
-	abs := embedding squaredLength.
-	abs = 0 ifTrue: [^ Float infinity].
-	otherAbs := anotherEmbedding squaredLength.
-	otherAbs = 0 ifTrue: [^ Float infinity].
-	^ 1.0 -
-		(
-			(embedding dot: anotherEmbedding)
-		/
-			(
-				abs
-			*
-				otherAbs
-			) sqrt
-		)
+	^ 1.0 - (embedding dot: anotherEmbedding)

packages/SemanticText.package/SemanticCorpus.class/instance/findAllDocuments.nearEmbedding..st

@@ -1,5 +1,6 @@
 search-embeddings
 findAllDocuments: number nearEmbedding: embedding
+	"Note: Ranking of results is invariant of length of the embedding argument."
 
 	| relatednesses |
 	relatednesses := Array new: self documents size streamContents: [:stream |

packages/SemanticText.package/SemanticCorpus.class/instance/findDocuments.similarTo.collect.thenSelect..st

@@ -10,7 +10,7 @@ findDocuments: number similarTo: documents collect: collectBlock thenSelect: sel
 	average := classifiedDocuments first embedding shallowCopy.
 	2 to: classifiedDocuments size do: [:i |
 		average += (classifiedDocuments at: i) embedding].
-	"average /= documents size." "NOT required because cosine distance only depends on vector direction"
+	"average /= documents size." "NOT required because ranking of results only depends on vector direction"
 
 	^ self
 		findDocuments: number

packages/SemanticText.package/SemanticCorpus.class/methodProperties.json

@@ -12,7 +12,7 @@
 		"addFragmentDocumentsFrom:title:content:as:" : "ct 8/14/2023 16:15",
 		"addFragmentDocumentsFromTitle:content:collect:" : "ct 8/14/2023 19:47",
 		"allDocumentsForObject:" : "ct 8/16/2023 20:07",
-		"distanceBetween:and:" : "ct 8/19/2023 22:09",
+		"distanceBetween:and:" : "ct 8/29/2023 17:32",
 		"documentClass" : "ct 8/14/2023 15:23",
 		"documents" : "ct 7/2/2023 17:41",
 		"documentsForObject:" : "ct 8/14/2023 16:30",
@@ -25,15 +25,15 @@
 		"estimateTimeToInitializeEmbeddingsFor:" : "ct 8/20/2023 21:00",
 		"estimateTokens" : "ct 8/20/2023 20:57",
 		"estimateTokensFor:" : "ct 8/27/2023 16:57",
-		"findAllDocuments:nearEmbedding:" : "ct 8/16/2023 19:03",
+		"findAllDocuments:nearEmbedding:" : "ct 8/29/2023 17:30",
 		"findClusteredDocuments:nearEmbedding:" : "ct 8/16/2023 19:12",
 		"findClusters:nearEmbedding:" : "ct 8/19/2023 22:09",
 		"findDocuments:nearEmbedding:" : "ct 8/16/2023 19:03",
 		"findDocuments:nearEmbedding:collect:" : "ct 8/17/2023 12:02",
 		"findDocuments:nearEmbedding:collect:thenSelect:" : "ct 8/19/2023 22:07",
 		"findDocuments:nearEmbedding:useClusters:" : "ct 8/16/2023 19:03",
 		"findDocuments:similarTo:collect:" : "ct 8/17/2023 12:03",
-		"findDocuments:similarTo:collect:thenSelect:" : "ct 8/19/2023 22:02",
+		"findDocuments:similarTo:collect:thenSelect:" : "ct 8/29/2023 19:51",
 		"findDocuments:similarToObject:collect:" : "ct 8/16/2023 20:02",
 		"findDocuments:similarToObjects:collect:" : "ct 8/16/2023 20:03",
 		"findDocuments:similarToQuery:collect:" : "ct 8/17/2023 20:35",

packages/SemanticText.package/SemanticMockEmbeddingModel.class/instance/getEmbeddingsForAll.config..st

@@ -1,15 +1,16 @@
 service
 getEmbeddingsForAll: strings config: aConfigOrNil
-	"Answer a collection with one embedding for each string. Each embedding vector is an array of numbers, commonly represented as a Float32Array."
+	"Answer a collection with one embedding for each string. Each embedding vector is an array of numbers, commonly represented as a Float32Array. Each vector is normalized, i.e., has a length very close to 1."
 
 	| config |
 	config := self baseConfig.
 	aConfigOrNil ifNotNil:
 		[config := config updatedWith: aConfigOrNil].
 
 	^ strings collect: [:string |
-		| words |
+		| words vector |
 		words := string substrings collect: [:word | word asLowercaseAlphabetic] as: Bag.
-		self keywords
+		vector := self keywords
 			collect: [:keyword | (words occurrencesOf: keyword) / words size]
-			as: Float32Array]
+			as: Float32Array.
+		vector /= vector length]

packages/SemanticText.package/SemanticMockEmbeddingModel.class/methodProperties.json

@@ -8,7 +8,7 @@
 		"getEmbeddingFor:" : "ct 8/20/2023 12:48",
 		"getEmbeddingFor:config:" : "ct 8/20/2023 12:52",
 		"getEmbeddingsForAll:" : "ct 8/20/2023 12:47",
-		"getEmbeddingsForAll:config:" : "ct 8/20/2023 13:03",
+		"getEmbeddingsForAll:config:" : "ct 8/29/2023 17:16",
 		"keywords" : "ct 8/17/2023 20:34",
 		"truncateString:minusString:minusWords:to:" : "ct 8/20/2023 13:11",
 		"truncateString:to:" : "ct 8/20/2023 13:11" } }