Source code for langchain_text_splitters.html

from __future__ import annotations

import copy
import pathlib
from io import BytesIO, StringIO
from typing import Any, Dict, Iterable, List, Optional, Tuple, TypedDict, cast

import requests
from langchain_core.documents import Document

from langchain_text_splitters.character import RecursiveCharacterTextSplitter


[docs]class ElementType(TypedDict): """Element type as typed dict.""" url: str xpath: str content: str metadata: Dict[str, str]
[docs]class HTMLHeaderTextSplitter: """ Splitting HTML files based on specified headers. Requires lxml package. """
[docs] def __init__( self, headers_to_split_on: List[Tuple[str, str]], return_each_element: bool = False, ): """Create a new HTMLHeaderTextSplitter. Args: headers_to_split_on: list of tuples of headers we want to track mapped to (arbitrary) keys for metadata. Allowed header values: h1, h2, h3, h4, h5, h6 e.g. [("h1", "Header 1"), ("h2", "Header 2)]. return_each_element: Return each element w/ associated headers. """ # Output element-by-element or aggregated into chunks w/ common headers self.return_each_element = return_each_element self.headers_to_split_on = sorted(headers_to_split_on)
[docs] def aggregate_elements_to_chunks( self, elements: List[ElementType] ) -> List[Document]: """Combine elements with common metadata into chunks Args: elements: HTML element content with associated identifying info and metadata """ aggregated_chunks: List[ElementType] = [] for element in elements: if ( aggregated_chunks and aggregated_chunks[-1]["metadata"] == element["metadata"] ): # If the last element in the aggregated list # has the same metadata as the current element, # append the current content to the last element's content aggregated_chunks[-1]["content"] += " \n" + element["content"] else: # Otherwise, append the current element to the aggregated list aggregated_chunks.append(element) return [ Document(page_content=chunk["content"], metadata=chunk["metadata"]) for chunk in aggregated_chunks ]
[docs] def split_text_from_url(self, url: str, **kwargs: Any) -> List[Document]: """Split HTML from web URL Args: url: web URL **kwargs: Arbitrary additional keyword arguments. These are usually passed to the fetch url content request. """ r = requests.get(url, **kwargs) return self.split_text_from_file(BytesIO(r.content))
[docs] def split_text(self, text: str) -> List[Document]: """Split HTML text string Args: text: HTML text """ return self.split_text_from_file(StringIO(text))
[docs] def split_text_from_file(self, file: Any) -> List[Document]: """Split HTML file Args: file: HTML file """ try: from lxml import etree except ImportError as e: raise ImportError( "Unable to import lxml, please install with `pip install lxml`." ) from e # use lxml library to parse html document and return xml ElementTree # Explicitly encoding in utf-8 allows non-English # html files to be processed without garbled characters parser = etree.HTMLParser(encoding="utf-8") tree = etree.parse(file, parser) # document transformation for "structure-aware" chunking is handled with xsl. # see comments in html_chunks_with_headers.xslt for more detailed information. xslt_path = pathlib.Path(__file__).parent / "xsl/html_chunks_with_headers.xslt" xslt_tree = etree.parse(xslt_path) transform = etree.XSLT(xslt_tree) result = transform(tree) result_dom = etree.fromstring(str(result)) # create filter and mapping for header metadata header_filter = [header[0] for header in self.headers_to_split_on] header_mapping = dict(self.headers_to_split_on) # map xhtml namespace prefix ns_map = {"h": "http://www.w3.org/1999/xhtml"} # build list of elements from DOM elements = [] for element in result_dom.findall("*//*", ns_map): if element.findall("*[@class='headers']") or element.findall( "*[@class='chunk']" ): elements.append( ElementType( url=file, xpath="".join( [ node.text or "" for node in element.findall("*[@class='xpath']", ns_map) ] ), content="".join( [ node.text or "" for node in element.findall("*[@class='chunk']", ns_map) ] ), metadata={ # Add text of specified headers to metadata using header # mapping. header_mapping[node.tag]: node.text or "" for node in filter( lambda x: x.tag in header_filter, element.findall("*[@class='headers']/*", ns_map), ) }, ) ) if not self.return_each_element: return self.aggregate_elements_to_chunks(elements) else: return [ Document(page_content=chunk["content"], metadata=chunk["metadata"]) for chunk in elements ]
[docs]class HTMLSectionSplitter: """ Splitting HTML files based on specified tag and font sizes. Requires lxml package. """
[docs] def __init__( self, headers_to_split_on: List[Tuple[str, str]], xslt_path: Optional[str] = None, **kwargs: Any, ) -> None: """Create a new HTMLSectionSplitter. Args: headers_to_split_on: list of tuples of headers we want to track mapped to (arbitrary) keys for metadata. Allowed header values: h1, h2, h3, h4, h5, h6 e.g. [("h1", "Header 1"), ("h2", "Header 2"]. xslt_path: path to xslt file for document transformation. Uses a default if not passed. Needed for html contents that using different format and layouts. """ self.headers_to_split_on = dict(headers_to_split_on) if xslt_path is None: self.xslt_path = ( pathlib.Path(__file__).parent / "xsl/converting_to_header.xslt" ).absolute() else: self.xslt_path = pathlib.Path(xslt_path).absolute() self.kwargs = kwargs
[docs] def split_documents(self, documents: Iterable[Document]) -> List[Document]: """Split documents.""" texts, metadatas = [], [] for doc in documents: texts.append(doc.page_content) metadatas.append(doc.metadata) results = self.create_documents(texts, metadatas=metadatas) text_splitter = RecursiveCharacterTextSplitter(**self.kwargs) return text_splitter.split_documents(results)
[docs] def split_text(self, text: str) -> List[Document]: """Split HTML text string Args: text: HTML text """ return self.split_text_from_file(StringIO(text))
[docs] def create_documents( self, texts: List[str], metadatas: Optional[List[dict]] = None ) -> List[Document]: """Create documents from a list of texts.""" _metadatas = metadatas or [{}] * len(texts) documents = [] for i, text in enumerate(texts): for chunk in self.split_text(text): metadata = copy.deepcopy(_metadatas[i]) for key in chunk.metadata.keys(): if chunk.metadata[key] == "#TITLE#": chunk.metadata[key] = metadata["Title"] metadata = {**metadata, **chunk.metadata} new_doc = Document(page_content=chunk.page_content, metadata=metadata) documents.append(new_doc) return documents
[docs] def split_html_by_headers(self, html_doc: str) -> List[Dict[str, Optional[str]]]: try: from bs4 import BeautifulSoup, PageElement # type: ignore[import-untyped] except ImportError as e: raise ImportError( "Unable to import BeautifulSoup/PageElement, \ please install with `pip install \ bs4`." ) from e soup = BeautifulSoup(html_doc, "html.parser") headers = list(self.headers_to_split_on.keys()) sections: list[dict[str, str | None]] = [] headers = soup.find_all(["body"] + headers) for i, header in enumerate(headers): header_element: PageElement = header if i == 0: current_header = "#TITLE#" current_header_tag = "h1" section_content: List = [] else: current_header = header_element.text.strip() current_header_tag = header_element.name section_content = [] for element in header_element.next_elements: if i + 1 < len(headers) and element == headers[i + 1]: break if isinstance(element, str): section_content.append(element) content = " ".join(section_content).strip() if content != "": sections.append( { "header": current_header, "content": content, "tag_name": current_header_tag, } ) return sections
[docs] def convert_possible_tags_to_header(self, html_content: str) -> str: if self.xslt_path is None: return html_content try: from lxml import etree except ImportError as e: raise ImportError( "Unable to import lxml, please install with `pip install lxml`." ) from e # use lxml library to parse html document and return xml ElementTree parser = etree.HTMLParser() tree = etree.parse(StringIO(html_content), parser) xslt_tree = etree.parse(self.xslt_path) transform = etree.XSLT(xslt_tree) result = transform(tree) return str(result)
[docs] def split_text_from_file(self, file: Any) -> List[Document]: """Split HTML file Args: file: HTML file """ file_content = file.getvalue() file_content = self.convert_possible_tags_to_header(file_content) sections = self.split_html_by_headers(file_content) return [ Document( cast(str, section["content"]), metadata={ self.headers_to_split_on[str(section["tag_name"])]: section[ "header" ] }, ) for section in sections ]