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chore: import upstream snapshot with attribution
2026-07-13 12:37:18 +08:00

56 lines
1.8 KiB
Python

"""Embedding utilities for testing."""
import math
import random
from collections import Counter, defaultdict
from typing import Any
from langchain_core.embeddings import Embeddings
class CharacterEmbeddings(Embeddings):
"""Simple character-frequency based embeddings using random projections."""
def __init__(self, dims: int = 50, seed: int = 42):
"""Initialize with embedding dimensions and random seed."""
self._rng = random.Random(seed)
self.dims = dims
# Create projection vector for each character lazily
self._char_projections: defaultdict[str, list[float]] = defaultdict(
lambda: [
self._rng.gauss(0, 1 / math.sqrt(self.dims)) for _ in range(self.dims)
]
)
def _embed_one(self, text: str) -> list[float]:
"""Embed a single text."""
counts = Counter(text)
total = sum(counts.values())
if total == 0:
return [0.0] * self.dims
embedding = [0.0] * self.dims
for char, count in counts.items():
weight = count / total
char_proj = self._char_projections[char]
for i, proj in enumerate(char_proj):
embedding[i] += weight * proj
norm = math.sqrt(sum(x * x for x in embedding))
if norm > 0:
embedding = [x / norm for x in embedding]
return embedding
def embed_documents(self, texts: list[str]) -> list[list[float]]:
"""Embed a list of documents."""
return [self._embed_one(text) for text in texts]
def embed_query(self, text: str) -> list[float]:
"""Embed a query string."""
return self._embed_one(text)
def __eq__(self, other: Any) -> bool:
return isinstance(other, CharacterEmbeddings) and self.dims == other.dims