community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)

Moved the following modules to new package langchain-community in a backwards compatible fashion:

```
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
```

Moved the following to core
```
mv langchain/langchain/utils/json_schema.py core/langchain_core/utils
mv langchain/langchain/utils/html.py core/langchain_core/utils
mv langchain/langchain/utils/strings.py core/langchain_core/utils
cat langchain/langchain/utils/env.py >> core/langchain_core/utils/env.py
rm langchain/langchain/utils/env.py
```

See .scripts/community_split/script_integrations.sh for all changes

libs/community/langchain_community/retrievers/tfidf.py

@@ -0,0 +1,127 @@
+from __future__ import annotations
+
+import pickle
+from pathlib import Path
+from typing import Any, Dict, Iterable, List, Optional
+
+from langchain_core.callbacks import CallbackManagerForRetrieverRun
+from langchain_core.documents import Document
+from langchain_core.retrievers import BaseRetriever
+
+
+class TFIDFRetriever(BaseRetriever):
+    """`TF-IDF` retriever.
+
+    Largely based on
+    https://github.com/asvskartheek/Text-Retrieval/blob/master/TF-IDF%20Search%20Engine%20(SKLEARN).ipynb
+    """
+
+    vectorizer: Any
+    """TF-IDF vectorizer."""
+    docs: List[Document]
+    """Documents."""
+    tfidf_array: Any
+    """TF-IDF array."""
+    k: int = 4
+    """Number of documents to return."""
+
+    class Config:
+        """Configuration for this pydantic object."""
+
+        arbitrary_types_allowed = True
+
+    @classmethod
+    def from_texts(
+        cls,
+        texts: Iterable[str],
+        metadatas: Optional[Iterable[dict]] = None,
+        tfidf_params: Optional[Dict[str, Any]] = None,
+        **kwargs: Any,
+    ) -> TFIDFRetriever:
+        try:
+            from sklearn.feature_extraction.text import TfidfVectorizer
+        except ImportError:
+            raise ImportError(
+                "Could not import scikit-learn, please install with `pip install "
+                "scikit-learn`."
+            )
+
+        tfidf_params = tfidf_params or {}
+        vectorizer = TfidfVectorizer(**tfidf_params)
+        tfidf_array = vectorizer.fit_transform(texts)
+        metadatas = metadatas or ({} for _ in texts)
+        docs = [Document(page_content=t, metadata=m) for t, m in zip(texts, metadatas)]
+        return cls(vectorizer=vectorizer, docs=docs, tfidf_array=tfidf_array, **kwargs)
+
+    @classmethod
+    def from_documents(
+        cls,
+        documents: Iterable[Document],
+        *,
+        tfidf_params: Optional[Dict[str, Any]] = None,
+        **kwargs: Any,
+    ) -> TFIDFRetriever:
+        texts, metadatas = zip(*((d.page_content, d.metadata) for d in documents))
+        return cls.from_texts(
+            texts=texts, tfidf_params=tfidf_params, metadatas=metadatas, **kwargs
+        )
+
+    def _get_relevant_documents(
+        self, query: str, *, run_manager: CallbackManagerForRetrieverRun
+    ) -> List[Document]:
+        from sklearn.metrics.pairwise import cosine_similarity
+
+        query_vec = self.vectorizer.transform(
+            [query]
+        )  # Ip -- (n_docs,x), Op -- (n_docs,n_Feats)
+        results = cosine_similarity(self.tfidf_array, query_vec).reshape(
+            (-1,)
+        )  # Op -- (n_docs,1) -- Cosine Sim with each doc
+        return_docs = [self.docs[i] for i in results.argsort()[-self.k :][::-1]]
+        return return_docs
+
+    def save_local(
+        self,
+        folder_path: str,
+        file_name: str = "tfidf_vectorizer",
+    ) -> None:
+        try:
+            import joblib
+        except ImportError:
+            raise ImportError(
+                "Could not import joblib, please install with `pip install joblib`."
+            )
+
+        path = Path(folder_path)
+        path.mkdir(exist_ok=True, parents=True)
+
+        # Save vectorizer with joblib dump.
+        joblib.dump(self.vectorizer, path / f"{file_name}.joblib")
+
+        # Save docs and tfidf array as pickle.
+        with open(path / f"{file_name}.pkl", "wb") as f:
+            pickle.dump((self.docs, self.tfidf_array), f)
+
+    @classmethod
+    def load_local(
+        cls,
+        folder_path: str,
+        file_name: str = "tfidf_vectorizer",
+    ) -> TFIDFRetriever:
+        try:
+            import joblib
+        except ImportError:
+            raise ImportError(
+                "Could not import joblib, please install with `pip install joblib`."
+            )
+
+        path = Path(folder_path)
+
+        # Load vectorizer with joblib load.
+        vectorizer = joblib.load(path / f"{file_name}.joblib")
+
+        # Load docs and tfidf array as pickle.
+        with open(path / f"{file_name}.pkl", "rb") as f:
+            docs, tfidf_array = pickle.load(f)
+
+        return cls(vectorizer=vectorizer, docs=docs, tfidf_array=tfidf_array)