Source code for langchain_community.document_loaders.bibtex

import logging
import re
from pathlib import Path
from typing import Any, Iterator, List, Mapping, Optional

from langchain_core.documents import Document

from langchain_community.document_loaders.base import BaseLoader
from langchain_community.utilities.bibtex import BibtexparserWrapper

logger = logging.getLogger(__name__)

[docs]class BibtexLoader(BaseLoader): """Load a `bibtex` file. Each document represents one entry from the bibtex file. If a PDF file is present in the `file` bibtex field, the original PDF is loaded into the document text. If no such file entry is present, the `abstract` field is used instead. """
[docs] def __init__( self, file_path: str, *, parser: Optional[BibtexparserWrapper] = None, max_docs: Optional[int] = None, max_content_chars: Optional[int] = 4_000, load_extra_metadata: bool = False, file_pattern: str = r"[^:]+\.pdf", ): """Initialize the BibtexLoader. Args: file_path: Path to the bibtex file. parser: The parser to use. If None, a default parser is used. max_docs: Max number of associated documents to load. Use -1 means no limit. max_content_chars: Maximum number of characters to load from the PDF. load_extra_metadata: Whether to load extra metadata from the PDF. file_pattern: Regex pattern to match the file name in the bibtex. """ self.file_path = file_path self.parser = parser or BibtexparserWrapper() self.max_docs = max_docs self.max_content_chars = max_content_chars self.load_extra_metadata = load_extra_metadata self.file_regex = re.compile(file_pattern)
def _load_entry(self, entry: Mapping[str, Any]) -> Optional[Document]: import fitz parent_dir = Path(self.file_path).parent # regex is useful for Zotero flavor bibtex files file_names = self.file_regex.findall(entry.get("file", "")) if not file_names: return None texts: List[str] = [] for file_name in file_names: try: with / file_name) as f: texts.extend(page.get_text() for page in f) except FileNotFoundError as e: logger.debug(e) content = "\n".join(texts) or entry.get("abstract", "") if self.max_content_chars: content = content[: self.max_content_chars] metadata = self.parser.get_metadata(entry, load_extra=self.load_extra_metadata) return Document( page_content=content, metadata=metadata, )
[docs] def lazy_load(self) -> Iterator[Document]: """Load bibtex file using bibtexparser and get the article texts plus the article metadata. See Returns: a list of documents with the document.page_content in text format """ try: import fitz # noqa: F401 except ImportError: raise ImportError( "PyMuPDF package not found, please install it with " "`pip install pymupdf`" ) entries = self.parser.load_bibtex_entries(self.file_path) if self.max_docs: entries = entries[: self.max_docs] for entry in entries: doc = self._load_entry(entry) if doc: yield doc