langchain/tests/integration_tests/vectorstores/fake_embeddings.py

"""Fake Embedding class for testing purposes."""
import math
from typing import List

from langchain.embeddings.base import Embeddings

fake_texts = ["foo", "bar", "baz"]


class FakeEmbeddings(Embeddings):
    """Fake embeddings functionality for testing."""

    def embed_documents(self, texts: List[str]) -> List[List[float]]:
        """Return simple embeddings.
        Embeddings encode each text as its index."""
        return [[float(1.0)] * 9 + [float(i)] for i in range(len(texts))]

    def embed_query(self, text: str) -> List[float]:
        """Return constant query embeddings.
        Embeddings are identical to embed_documents(texts)[0].
        Distance to each text will be that text's index,
        as it was passed to embed_documents."""
        return [float(1.0)] * 9 + [float(0.0)]


class ConsistentFakeEmbeddings(FakeEmbeddings):
    """Fake embeddings which remember all the texts seen so far to return consistent
    vectors for the same texts."""

    def __init__(self, dimensionality: int = 10) -> None:
        self.known_texts: List[str] = []
        self.dimensionality = dimensionality

    def embed_documents(self, texts: List[str]) -> List[List[float]]:
        """Return consistent embeddings for each text seen so far."""
        out_vectors = []
        for text in texts:
            if text not in self.known_texts:
                self.known_texts.append(text)
            vector = [float(1.0)] * (self.dimensionality - 1) + [
                float(self.known_texts.index(text))
            ]
            out_vectors.append(vector)
        return out_vectors

    def embed_query(self, text: str) -> List[float]:
        """Return consistent embeddings for the text, if seen before, or a constant
        one if the text is unknown."""
        if text not in self.known_texts:
            return [float(1.0)] * (self.dimensionality - 1) + [float(0.0)]
        return [float(1.0)] * (self.dimensionality - 1) + [
            float(self.known_texts.index(text))
        ]


class AngularTwoDimensionalEmbeddings(Embeddings):
    """
    From angles (as strings in units of pi) to unit embedding vectors on a circle.
    """

    def embed_documents(self, texts: List[str]) -> List[List[float]]:
        """
        Make a list of texts into a list of embedding vectors.
        """
        return [self.embed_query(text) for text in texts]

    def embed_query(self, text: str) -> List[float]:
        """
        Convert input text to a 'vector' (list of floats).
        If the text is a number, use it as the angle for the
        unit vector in units of pi.
        Any other input text becomes the singular result [0, 0] !
        """
        try:
            angle = float(text)
            return [math.cos(angle * math.pi), math.sin(angle * math.pi)]
        except ValueError:
            # Assume: just test string, no attention is paid to values.
            return [0.0, 0.0]