add cookbook for selectins llms based on context length (#12486)

cookbook/selecting_llms_based_on_context_length.ipynb

@@ -0,0 +1,175 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "e93283d1",
+   "metadata": {},
+   "source": [
+    "# Selecting LLMs based on Context Length\n",
+    "\n",
+    "Different LLMs have different context lengths. As a very immediate an practical example, OpenAI has two versions of GPT-3.5-Turbo: one with 4k context, another with 16k context. This notebook shows how to route between them based on input."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 24,
+   "id": "cc453450",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.prompts import PromptTemplate\n",
+    "from langchain.schema.prompt import PromptValue\n",
+    "from langchain.schema.messages import BaseMessage\n",
+    "from langchain.chat_models import ChatOpenAI\n",
+    "from langchain.schema.output_parser import StrOutputParser\n",
+    "from typing import Union, Sequence"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "1cec6a10",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "short_context_model = ChatOpenAI(model=\"gpt-3.5-turbo\")\n",
+    "long_context_model = ChatOpenAI(model=\"gpt-3.5-turbo-16k\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "id": "772da153",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def get_context_length(prompt: PromptValue):\n",
+    "    messages = prompt.to_messages()\n",
+    "    tokens = short_context_model.get_num_tokens_from_messages(messages)\n",
+    "    return tokens"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "id": "db771e20",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "prompt = PromptTemplate.from_template(\"Summarize this passage: {context}\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "id": "af057e2f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def choose_model(prompt: PromptValue):\n",
+    "    context_len = get_context_length(prompt)\n",
+    "    if context_len < 30:\n",
+    "        print(\"short model\")\n",
+    "        return short_context_model\n",
+    "    else:\n",
+    "        print(\"long model\")\n",
+    "        return long_context_model"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 25,
+   "id": "84f3e07d",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "chain = prompt | choose_model | StrOutputParser()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 26,
+   "id": "d8b14f8f",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "short model\n"
+     ]
+    },
+    {
+     "data": {
+      "text/plain": [
+       "'The passage mentions that a frog visited a pond.'"
+      ]
+     },
+     "execution_count": 26,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "chain.invoke({\"context\": \"a frog went to a pond\"})"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 27,
+   "id": "70ebd3dd",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "long model\n"
+     ]
+    },
+    {
+     "data": {
+      "text/plain": [
+       "'The passage describes a frog that moved from one pond to another and perched on a log.'"
+      ]
+     },
+     "execution_count": 27,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "chain.invoke({\"context\": \"a frog went to a pond and sat on a log and went to a different pond\"})"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "a7e29fef",
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "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": "3.10.1"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}