Source code for langchain.vectorstores.faiss
"""Wrapper around FAISS vector database."""
from __future__ import annotations
import math
import os
import pickle
import uuid
from pathlib import Path
from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple
import numpy as np
from langchain.docstore.base import AddableMixin, Docstore
from langchain.docstore.document import Document
from langchain.docstore.in_memory import InMemoryDocstore
from langchain.embeddings.base import Embeddings
from langchain.vectorstores.base import VectorStore
from langchain.vectorstores.utils import maximal_marginal_relevance
def dependable_faiss_import(no_avx2: Optional[bool] = None) -> Any:
    """
    Import faiss if available, otherwise raise error.
    If FAISS_NO_AVX2 environment variable is set, it will be considered
    to load FAISS with no AVX2 optimization.
    Args:
        no_avx2: Load FAISS strictly with no AVX2 optimization
            so that the vectorstore is portable and compatible with other devices.
    """
    if no_avx2 is None and "FAISS_NO_AVX2" in os.environ:
        no_avx2 = bool(os.getenv("FAISS_NO_AVX2"))
    try:
        if no_avx2:
            from faiss import swigfaiss as faiss
        else:
            import faiss
    except ImportError:
        raise ValueError(
            "Could not import faiss python package. "
            "Please install it with `pip install faiss` "
            "or `pip install faiss-cpu` (depending on Python version)."
        )
    return faiss
def _default_relevance_score_fn(score: float) -> float:
rtdocs_stable/api.python.langchain.com/en/stable/_modules/langchain/vectorstores/faiss.html