From 1bd3b5d0ee9395ed5bce48eadc5c4e58f5385099 Mon Sep 17 00:00:00 2001
From: vinodkiran <vinodkiran@usa.net>
Date: Sat, 30 Dec 2023 08:07:15 +0530
Subject: [PATCH] Compression Retriever: Addition of constant to RRF Retriever

---
 .../retrievers/RRFRetriever/RRFRetriever.ts      | 16 +++++++++++++++-
 .../RRFRetriever/ReciprocalRankFusion.ts         |  6 ++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/packages/components/nodes/retrievers/RRFRetriever/RRFRetriever.ts b/packages/components/nodes/retrievers/RRFRetriever/RRFRetriever.ts
index 8d6d9d6f..3229b3a8 100644
--- a/packages/components/nodes/retrievers/RRFRetriever/RRFRetriever.ts
+++ b/packages/components/nodes/retrievers/RRFRetriever/RRFRetriever.ts
@@ -57,6 +57,18 @@ class RRFRetriever_Retrievers implements INode {
                 default: 0,
                 additionalParams: true,
                 optional: true
+            },
+            {
+                label: 'Constant',
+                name: 'c',
+                description:
+                    'A constant added to the rank, controlling the balance between the importance of high-ranked items and the consideration given to lower-ranked items.\n' +
+                    'Default is 60',
+                placeholder: '60',
+                type: 'number',
+                default: 60,
+                additionalParams: true,
+                optional: true
             }
         ]
     }
@@ -68,12 +80,14 @@ class RRFRetriever_Retrievers implements INode {
         const q = queryCount ? parseFloat(queryCount) : 4
         const topK = nodeData.inputs?.topK as string
         let k = topK ? parseFloat(topK) : 4
+        const constantC = nodeData.inputs?.c as string
+        let c = topK ? parseFloat(constantC) : 60
 
         if (k <= 0) {
             k = (baseRetriever as VectorStoreRetriever).k
         }
 
-        const ragFusion = new ReciprocalRankFusion(llm, baseRetriever as VectorStoreRetriever, q, k)
+        const ragFusion = new ReciprocalRankFusion(llm, baseRetriever as VectorStoreRetriever, q, k, c)
         return new ContextualCompressionRetriever({
             baseCompressor: ragFusion,
             baseRetriever: baseRetriever
diff --git a/packages/components/nodes/retrievers/RRFRetriever/ReciprocalRankFusion.ts b/packages/components/nodes/retrievers/RRFRetriever/ReciprocalRankFusion.ts
index 134d7c8a..b14608fe 100644
--- a/packages/components/nodes/retrievers/RRFRetriever/ReciprocalRankFusion.ts
+++ b/packages/components/nodes/retrievers/RRFRetriever/ReciprocalRankFusion.ts
@@ -10,13 +10,15 @@ export class ReciprocalRankFusion extends BaseDocumentCompressor {
     private readonly llm: BaseLanguageModel
     private readonly queryCount: number
     private readonly topK: number
+    private readonly c: number
     private baseRetriever: VectorStoreRetriever
-    constructor(llm: BaseLanguageModel, baseRetriever: VectorStoreRetriever, queryCount: number, topK: number) {
+    constructor(llm: BaseLanguageModel, baseRetriever: VectorStoreRetriever, queryCount: number, topK: number, c: number) {
         super()
         this.queryCount = queryCount
         this.llm = llm
         this.baseRetriever = baseRetriever
         this.topK = topK
+        this.c = c
     }
     async compressDocuments(
         documents: Document<Record<string, any>>[],
@@ -57,7 +59,7 @@ export class ReciprocalRankFusion extends BaseDocumentCompressor {
             docList.push(docs)
         }
 
-        return this.reciprocalRankFunction(docList, 60)
+        return this.reciprocalRankFunction(docList, this.c)
     }
 
     reciprocalRankFunction(docList: Document<Record<string, any>>[][], k: number): Document<Record<string, any>>[] {