haystack/tutorials/Tutorial1_Basic_QA_Pipeline.py

# ## Task: Question Answering for Game of Thrones
#
# Question Answering can be used in a variety of use cases. A very common one:  Using it to navigate through complex
# knowledge bases or long documents ("search setting").
#
# A "knowledge base" could for example be your website, an internal wiki or a collection of financial reports.
# In this tutorial we will work on a slightly different domain: "Game of Thrones".
#
# Let's see how we can use a bunch of Wikipedia articles to answer a variety of questions about the
# marvellous seven kingdoms...

import logging
import subprocess
import time

from haystack import Finder
from haystack.document_store.elasticsearch import ElasticsearchDocumentStore
from haystack.preprocessor.cleaning import clean_wiki_text
from haystack.preprocessor.utils import convert_files_to_dicts, fetch_archive_from_http
from haystack.reader.farm import FARMReader
from haystack.reader.transformers import TransformersReader
from haystack.utils import print_answers
from haystack.retriever.sparse import ElasticsearchRetriever

logger = logging.getLogger(__name__)

LAUNCH_ELASTICSEARCH = True

# ## Document Store
#
# Haystack finds answers to queries within the documents stored in a `DocumentStore`. The current implementations of
# `DocumentStore` include `ElasticsearchDocumentStore`, `FAISSDocumentStore`, `SQLDocumentStore`, and `InMemoryDocumentStore`.
#
# **Here:** We recommended Elasticsearch as it comes preloaded with features like full-text queries, BM25 retrieval,
# and vector storage for text embeddings.
# **Alternatives:** If you are unable to setup an Elasticsearch instance, then follow the Tutorial 3
# for using SQL/InMemory document stores.
# **Hint**:
# This tutorial creates a new document store instance with Wikipedia articles on Game of Thrones. However, you can
# configure Haystack to work with your existing document stores.
#
# Start an Elasticsearch server
# You can start Elasticsearch on your local machine instance using Docker. If Docker is not readily available in
# your environment (eg., in Colab notebooks), then you can manually download and execute Elasticsearch from source.

if LAUNCH_ELASTICSEARCH:
    logging.info("Starting Elasticsearch ...")
    status = subprocess.run(
        ['docker run -d -p 9200:9200 -e "discovery.type=single-node" elasticsearch:7.6.2'], shell=True
    )
    if status.returncode:
        raise Exception("Failed to launch Elasticsearch. If you want to connect to an existing Elasticsearch instance"
                        "then set LAUNCH_ELASTICSEARCH in the script to False.")
    time.sleep(15)

# Connect to Elasticsearch
document_store = ElasticsearchDocumentStore(host="localhost", username="", password="", index="document")

# ## Preprocessing of documents
#
# Haystack provides a customizable pipeline for:
# - converting files into texts
# - cleaning texts
# - splitting texts
# - writing them to a Document Store

# In this tutorial, we download Wikipedia articles about Game of Thrones, apply a basic cleaning function, and add
# them in Elasticsearch.


# Let's first fetch some documents that we want to query
# Here: 517 Wikipedia articles for Game of Thrones
doc_dir = "data/article_txt_got"
s3_url = "https://s3.eu-central-1.amazonaws.com/deepset.ai-farm-qa/datasets/documents/wiki_gameofthrones_txt.zip"
fetch_archive_from_http(url=s3_url, output_dir=doc_dir)

# convert files to dicts containing documents that can be indexed to our datastore
dicts = convert_files_to_dicts(dir_path=doc_dir, clean_func=clean_wiki_text, split_paragraphs=True)
# You can optionally supply a cleaning function that is applied to each doc (e.g. to remove footers)
# It must take a str as input, and return a str.

# Now, let's write the docs to our DB.
if LAUNCH_ELASTICSEARCH:
    document_store.write_documents(dicts)
else:
    logger.warning("Since we already have a running ES instance we should not index the same documents again. \n"
                   "If you still want to do this call: document_store.write_documents(dicts) manually ")

# ## Initalize Retriever, Reader,  & Finder
#
# ### Retriever
#
# Retrievers help narrowing down the scope for the Reader to smaller units of text where a given question
# could be answered.
#
# They use some simple but fast algorithm.
# **Here:** We use Elasticsearch's default BM25 algorithm
# **Alternatives:**
# - Customize the `ElasticsearchRetriever`with custom queries (e.g. boosting) and filters
# - Use `EmbeddingRetriever` to find candidate documents based on the similarity of
#   embeddings (e.g. created via Sentence-BERT)
# - Use `TfidfRetriever` in combination with a SQL or InMemory Document store for simple prototyping and debugging

retriever = ElasticsearchRetriever(document_store=document_store)

# Alternative: An in-memory TfidfRetriever based on Pandas dataframes for building quick-prototypes
# with SQLite document store.
#
# from haystack.retriever.tfidf import TfidfRetriever
# retriever = TfidfRetriever(document_store=document_store)

# ### Reader
#
# A Reader scans the texts returned by retrievers in detail and extracts the k best answers. They are based
# on powerful, but slower deep learning models.
#
# Haystack currently supports Readers based on the frameworks FARM and Transformers.
# With both you can either load a local model or one from Hugging Face's model hub (https://huggingface.co/models).
# **Here:** a medium sized RoBERTa QA model using a Reader based on
#           FARM (https://huggingface.co/deepset/roberta-base-squad2)
# **Alternatives (Reader):** TransformersReader (leveraging the `pipeline` of the Transformers package)
# **Alternatives (Models):** e.g. "distilbert-base-uncased-distilled-squad" (fast) or
#                            "deepset/bert-large-uncased-whole-word-masking-squad2" (good accuracy)
# **Hint:** You can adjust the model to return "no answer possible" with the no_ans_boost. Higher values mean
#           the model prefers "no answer possible"
#
# #### FARMReader

# Load a  local model or any of the QA models on
# Hugging Face's model hub (https://huggingface.co/models)
reader = FARMReader(model_name_or_path="deepset/roberta-base-squad2", use_gpu=False)

# #### TransformersReader

# Alternative:
# reader = TransformersReader(
#    model_name_or_path="distilbert-base-uncased-distilled-squad", tokenizer="distilbert-base-uncased", use_gpu=-1)

# ### Finder
#
# The Finder sticks together reader and retriever in a pipeline to answer our actual questions.

finder = Finder(reader, retriever)

# ## Voilà! Ask a question!
# You can configure how many candidates the reader and retriever shall return
# The higher top_k_retriever, the better (but also the slower) your answers.
prediction = finder.get_answers(question="Who is the father of Sansa Stark?", top_k_retriever=10, top_k_reader=5)


# prediction = finder.get_answers(question="Who created the Dothraki vocabulary?", top_k_reader=5)
# prediction = finder.get_answers(question="Who is the sister of Sansa?", top_k_reader=5)

print_answers(prediction, details="minimal")