rag_server/applications/utils/chunks/topic_aware_chunking.py

"""
主题感知分块
"""

from __future__ import annotations

from typing import List, Dict, Any

import numpy as np

from applications.api import get_basic_embedding
from applications.config import DEFAULT_MODEL, Chunk
from applications.utils.nlp import SplitTextIntoSentences, num_tokens, BoundaryDetector


class TopicAwareChunker(BoundaryDetector, SplitTextIntoSentences):
    INIT_STATUS = 0
    PROCESSING_STATUS = 1
    FINISHED_STATUS = 2
    FAILED_STATUS = 3

    def __init__(self, doc_id: str):
        super().__init__()
        self.doc_id = doc_id

    @staticmethod
    async def _encode_batch(texts: List[str]) -> np.ndarray:
        embs = []
        for t in texts:
            e = await get_basic_embedding(t, model=DEFAULT_MODEL)
            embs.append(np.array(e, dtype=np.float32))
        return np.stack(embs)

    async def _raw_chunk(self, text: str) -> Dict[str, Any]:
        sentence_list = self.jieba_sent_tokenize(text)
        if not sentence_list:
            return {}

        sentences_embeddings = await self._encode_batch(sentence_list)
        boundaries = self.detect_boundaries(sentence_list, sentences_embeddings)
        return {
            "sentence_list": sentence_list,
            "boundaries": boundaries,
            "embeddings": sentences_embeddings,
        }


class TopicAwarePackerV1(TopicAwareChunker):
    def _pack_v1(
        self,
        sentence_list: List[str],
        boundaries: List[int],
        text_type: int,
        dataset_id: int,
    ) -> List[Chunk]:
        boundary_set = set(boundaries)
        chunks: List[Chunk] = []
        start = 0
        n = len(sentence_list)
        chunk_id = 0
        while start < n:
            end = start
            sent_count = 0
            while end < n and sent_count < self.max_sent_per_chunk:
                cur_tokens = num_tokens(" ".join(sentence_list[start : end + 1]))
                sent_count += 1
                if cur_tokens >= self.target_tokens:
                    cut = end
                    for b in range(end, start - 1, -1):
                        if b in boundary_set:
                            cut = b
                            break
                    if cut - start + 1 >= self.min_sent_per_chunk:
                        end = cut
                    break
                end += 1

            text = " ".join(sentence_list[start : end + 1]).strip()
            tokens = num_tokens(text)
            chunk_id += 1
            chunk = Chunk(
                doc_id=self.doc_id,
                chunk_id=chunk_id,
                text=text,
                tokens=tokens,
                text_type=text_type,
                dataset_id=dataset_id,
            )
            chunks.append(chunk)
            start = end + 1
        return chunks

    async def chunk(self, text: str, text_type: int, dataset_id: int) -> List[Chunk]:
        raw_info = await self._raw_chunk(text)
        if not raw_info:
            return []

        return self._pack_v1(
            sentence_list=raw_info["sentence_list"],
            boundaries=raw_info["boundaries"],
            text_type=text_type,
            dataset_id=dataset_id,
        )


class TopicAwarePackerV2(TopicAwareChunker):
    def _pack_v2(
        self,
        sentence_list: List[str],
        boundaries: List[int],
        embeddings: np.ndarray,
        text_type: int,
        dataset_id: int,
    ) -> List[Chunk]:
        segments = []
        seg_embs = []
        last_idx = 0
        for b in boundaries + [len(sentence_list) - 1]:
            seg = sentence_list[last_idx : b + 1]
            seg_emb = np.mean(embeddings[last_idx : b + 1], axis=0)
            if seg:
                segments.append(seg)
                seg_embs.append(seg_emb)
            last_idx = b + 1

        final_segments = []
        for seg in segments:
            tokens = num_tokens("".join(seg))
            if tokens > self.max_tokens and len(seg) > 1:
                mid = len(seg) // 2
                final_segments.append(seg[:mid])
                final_segments.append(seg[mid:])
            else:
                final_segments.append(seg)

        chunks = []
        for index, seg in enumerate(final_segments, 1):
            text = "".join(seg)
            tokens = num_tokens(text)
            # 如果 token 过短，则暂时不用
            status = 2 if tokens < self.min_tokens else 1
            chunks.append(
                Chunk(
                    doc_id=self.doc_id,
                    dataset_id=dataset_id,
                    text=text,
                    chunk_id=index,
                    tokens=num_tokens(text),
                    text_type=text_type,
                    status=status,
                )
            )

        return chunks

    async def chunk(self, text: str, text_type: int, dataset_id: int) -> List[Chunk]:
        raw_info = await self._raw_chunk(text)
        if not raw_info:
            return []

        return self._pack_v2(
            sentence_list=raw_info["sentence_list"],
            boundaries=raw_info["boundaries"],
            embeddings=raw_info["embeddings"],
            text_type=text_type,
            dataset_id=dataset_id,
        )