RAG (Retrieval, Augmentation, and Generation) is the combination of retrieval techniques with generation to produce more accurate answers or text. In this project, the input is a PDF, and the output is an answer generated based on the received input.

RAG with Langchain

!pip install -qU langchain-openai pypdf langchain_community

Load

from langchain_community.document_loaders import PyPDFLoader

file_path = "/content/katalog_mobil.pdf"
loader = PyPDFLoader(file_path)

docs = loader.load()

print(len(docs))

docs

Output:

[Document(metadata={'source': '/content/katalog_mobil.pdf', 'page': 0}, page_content=' SURAT KEPUTUSAN  NO. SK/001/TSO.OPR/I/2023 \n HARGA KENDARAAN TOYOTA   REGULAR ORDER  WILAYAH : JAKARTA, BEKASI, BANTEN B (PLAT NOMOR "B")  Per 1 Januari 2023 \n TYPE  ON THE ROAD  KETERANGAN All New Vios 1.5 G CVT (Non Premium Color)NGC102GA/T00 355.200.000                            All New Vios 1.5 G CVT (Premium Color) NGC102GA/T02 356.700.000                            All New Vios 1.5 G TSS CVT (Non Premium Color)NGC102GA/T01 368.400.000                            All New Vios 1.5 G TSS CVT (Premium Color)NGC102GA/T03 369.900.000                            COROLLA ALTIS 1.8 V A/T (Non Premium Color)ZE211VA/T14 538.900.000                            COROLLA ALTIS 1.8L HYBRID A/T (Non Premium Color)ZE211LA/T12 593.300.000                            COROLLA CROSS 1.8 HYBRID A/T (Non Premium Color)ZVG10A/T01 540.900.000                            COROLLA CROSS 1.8 HYBRID A/T (Premium Color)ZVG10A/T02 543.800.000                            CAMRY 2.5 V A/T (Non Premium Color) AX70VA/T00 771.300.000                            CAMRY 2.5 V A/T (Premium Color) AX70VA/T01 774.400.000                            CAMRY 2.5 L A/T HYBRID (Non Premium Color)AV71LA/T00 909.400.000                            CAMRY 2.5 L A/T HYBRID (Premium Color) AV71LA/T01 912.400.000 ...

import getpass
import os
from google.colab import userdata

os.environ["OPENAI_API_KEY"] = userdata.get('OPENAI_API_KEY')

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(model="gpt-4o")

Split, Embed, Store

from langchain_core.vectorstores import InMemoryVectorStore
from langchain_openai import OpenAIEmbeddings
from langchain_text_splitters import RecursiveCharacterTextSplitter

text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
splits = text_splitter.split_documents(docs)
vectorstore = InMemoryVectorStore.from_documents(
    documents=splits, embedding=OpenAIEmbeddings()
)

retriever = vectorstore.as_retriever()

Retrieve and Generate

from langchain.chains import create_retrieval_chain
from langchain.chains.combine_documents import create_stuff_documents_chain
from langchain_core.prompts import ChatPromptTemplate

system_prompt = (
    "You are an assistant for question-answering tasks. "
    "Use the following pieces of retrieved context to answer "
    "the question. If you don't know the answer, say that you "
    "don't know. Use three sentences maximum and keep the "
    "answer concise."
    "\n\n"
    "{context}"
)

prompt = ChatPromptTemplate.from_messages(
    [
        ("system", system_prompt),
        ("human", "{input}"),
    ]
)


question_answer_chain = create_stuff_documents_chain(llm, prompt)
rag_chain = create_retrieval_chain(retriever, question_answer_chain)

results = rag_chain.invoke({"input": "Berapa harga mobile All New Vios?"})

results

Output

{'input': 'Berapa harga mobile All New Vios?',
 'context': [Document(id='ec435d7b-e222-45e3-9ef9-30172ee25000', metadata={'source': '/content/katalog_mobil.pdf', 'page': 0}, page_content='TYPE  ON THE ROAD  KETERANGAN All New Vios 1.5 G CVT (Non Premium Color)NGC102GA/T00 355.200.000                            All New Vios 1.5 G CVT (Premium Color) NGC102GA/T02 356.700.000                            All New Vios 1.5 G TSS CVT (Non Premium Color)NGC102GA/T01 368.400.000                            All New Vios 1.5 G TSS CVT (Premium Color)NGC102GA/T03 369.900.000                            COROLLA ALTIS 1.8 V A/T (Non Premium Color)ZE211VA/T14 538.900.000                            COROLLA ALTIS 1.8L HYBRID A/T (Non Premium Color)ZE211LA/T12 593.300.000                            COROLLA CROSS 1.8 HYBRID A/T (Non Premium Color)ZVG10A/T01 540.900.000                            COROLLA CROSS 1.8 HYBRID A/T (Premium Color)ZVG10A/T02 543.800.000                            CAMRY 2.5 V A/T (Non Premium Color) AX70VA/T00 771.300.000                            CAMRY 2.5 V A/T (Premium Color) AX70VA/T01 774.400.000                            CAMRY 2.5 L A/T HYBRID (Non Premium'),
  Document(id='4a99b826-c07d-478c-aaae-88588955deb4', metadata={'source': '/content/katalog_mobil.pdf', 'page': 1}, page_content='TYPE  ON THE ROAD  KETERANGAN All New Vios 1.5 E M/T NGC102EM/T00 314.900.000                            COROLLA ALTIS 1.8 V A/T (Premium Color)ZE211VA/T15 541.900.000                            COROLLA ALTIS 1.8L HYBRID A/T (Premium Color)ZE211LA/T13 596.300.000                            AGYA 1.2 G A/T STD B101GA/T10 173.300.000                             YARIS 1.5 S M/T GR SPORT 3 Airbags NSP15SM/T51 308.100.000                             YARIS 1.5 G CVT 3 Airbags NSR15GA/T21 295.800.000                            AVANZA 1.5 G CVT TSS W01GA/T01 295.800.000                            KIJANG INNOVA 2.0 G M/T BSN TGN40GM/T30X 369.900.000                            KIJANG INNOVA 2.4 G M/T DSL GUN14GM/T20X 397.400.000                            SIENTA 1.5 V CVT NSP70VA/T17 325.400.000                            SIENTA 1.5 Q CVT NSP70QA/T17 347.000.000                            SIENTA 1.5 V CVT WELCAB DISABILITY NSP70VA/T18 419.900.000                            VELLFIRE 2.5 G A/T'),
  Document(id='0baea8bd-e7f5-421d-9bc1-11a5b7c6140f', metadata={'source': '/content/katalog_mobil.pdf', 'page': 0}, page_content='CABIN 2.4 V (4x4) DSL A/T GUN25DCVA/T30 520.800.000                            LAND CRUISER 300 VX-R 4x4 A/T (Non Premium Color)FJA300VXA/T04 2.453.500.000                       LAND CRUISER 300 VX-R 4x4 A/T  (Premium Color)FJA300VXA/T05 2.456.500.000                       LAND CRUISER 300 VX-R 4x4 A/T (Non Premium Color)FJA300VXA/T24 2.453.500.000                       LAND CRUISER 300 VX-R 4x4 A/T  (Premium Color)FJA300VXA/T25 2.456.500.000                       LAND CRUISER 300 GR-S 4x4 A/T  (Non Premium Color)FJA300GRA/T08 2.512.700.000                       LAND CRUISER 300 GR-S 4x4 A/T  (Premium Color)FJA300GRA/T09 2.515.700.000                       HI ACE COMMUTER M/T KD223M/T00COMM551.200.000                            HI ACE PREMIO 2.8 M/T GD321M/T00 636.900.000                            Jakarta, 1 Januari 20231. Harga sewaktu-waktu dapat berubah.2. Dyna, Hilux, Hi Ace sudah termasuk Keur.3. LC 300 unit tergantung ketersediaan barang'),
  Document(id='dfebb724-538b-4cf5-8b37-ecc683ea06a7', metadata={'source': '/content/katalog_mobil.pdf', 'page': 2}, page_content='VOXY 2.0 A/T LUX (Premium Color) MZR90A/T01 598.500.000                            Voxy Basic +  Aksesoris LuxVELLFIRE 2.5 G A/T LUX VER30GA/T00 1.402.600.000                       Vellfire Basic + Aksesoris LuxALPHARD 2.5 G A/T LUX (Non Premium Color)AL30GA/T30 1.387.800.000                       ALPHARD 2.5 G A/T LUX (Premium Color) AL30GA/T31 1.390.900.000                       RAIZE 1.2 G CVT ONE TONE LUX A251GA/T00SY 254.046.000                            RAIZE 1.0T G M/T ONE TONE LUX A250GM/T00SY 258.646.000                            RAIZE 1.0T G CVT ONE TONE LUX A250GA/T00SY 273.646.000                            RAIZE 1.0T GR SPORT CVT ONE TONE LUX A250SA/T20Y 287.546.000                            RAIZE 1.0T GR SPORT CVT TWO TONE LUX A250SA/T21Y 290.146.000                            RAIZE 1.0T GR SPORT CVT TSS TWO TONE LUXA250SA/T23Y 311.846.000                            RUSH 1.5 G M/T LUX F80GM/T20 281.409.000                            RUSH 1.5 G A/T')],
 'answer': 'Harga All New Vios bervariasi tergantung tipe dan warna. All New Vios 1.5 E M/T dibanderol 314.900.000, sementara All New Vios 1.5 G CVT (Non Premium Color) seharga 355.200.000 dan versi Premium Color 356.700.000. Untuk tipe All New Vios 1.5 G TSS CVT, harga Non Premium Color adalah 368.400.000 dan Premium Color 369.900.000.'}

Google Colab 👉 RAG-Langchain