Create merge loader that combines documents from a set of loaders (#6659)

Simple utility loader that combines documents from a set of specified
loaders.

docs/extras/modules/data_connection/document_loaders/integrations/merge_doc_loader.ipynb

@@ -0,0 +1,99 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "dd7c3503",
+   "metadata": {},
+   "source": [
+    "# MergeDocLoader\n",
+    "\n",
+    "Merge the documents returned from a set of specified data loaders."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "e08dfff1",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.document_loaders import WebBaseLoader\n",
+    "loader_web = WebBaseLoader(\"https://github.com/basecamp/handbook/blob/master/37signals-is-you.md\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "07b42b2e",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.document_loaders import PyPDFLoader\n",
+    "loader_pdf = PyPDFLoader(\"../MachineLearning-Lecture01.pdf\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "912ede96",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.document_loaders.merge import MergedDataLoader\n",
+    "loader_all=MergedDataLoader(loaders=[loader_web,loader_pdf])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "id": "9d001311",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "docs_all=loader_all.load()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "id": "b9097486",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "23"
+      ]
+     },
+     "execution_count": 8,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "len(docs_all)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.9.16"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

langchain/document_loaders/__init__.py

@@ -67,6 +67,7 @@ from langchain.document_loaders.markdown import UnstructuredMarkdownLoader
 from langchain.document_loaders.mastodon import MastodonTootsLoader
 from langchain.document_loaders.max_compute import MaxComputeLoader
 from langchain.document_loaders.mediawikidump import MWDumpLoader
+from langchain.document_loaders.merge import MergedDataLoader
 from langchain.document_loaders.modern_treasury import ModernTreasuryLoader
 from langchain.document_loaders.notebook import NotebookLoader
 from langchain.document_loaders.notion import NotionDirectoryLoader
@@ -201,6 +202,7 @@ __all__ = [
     "MastodonTootsLoader",
     "MathpixPDFLoader",
     "MaxComputeLoader",
+    "MergedDataLoader",
     "ModernTreasuryLoader",
     "NotebookLoader",
     "NotionDBLoader",

langchain/document_loaders/merge.py

@@ -0,0 +1,27 @@
+from typing import Iterator, List
+
+from langchain.docstore.document import Document
+from langchain.document_loaders.base import BaseLoader
+
+
+class MergedDataLoader(BaseLoader):
+    """Merge documents from a list of loaders"""
+
+    def __init__(self, loaders: List):
+        """Initialize with a list of loaders"""
+        self.loaders = loaders
+
+    def lazy_load(self) -> Iterator[Document]:
+        """Lazy load docs from each individual loader."""
+        for loader in self.loaders:
+            # Check if lazy_load is implemented
+            try:
+                data = loader.lazy_load()
+            except NotImplementedError:
+                data = loader.load()
+            for document in data:
+                yield document
+
+    def load(self) -> List[Document]:
+        """Load docs."""
+        return list(self.lazy_load())