langchain/docs/modules/chains/generic/sequential_chains.ipynb

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   "source": [
    "# Sequential Chains"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "3b235f7a",
   "metadata": {},
   "source": [
    "The next step after calling a language model is make a series of calls to a language model. This is particularly useful when you want to take the output from one call and use it as the input to another.\n",
    "\n",
    "In this notebook we will walk through some examples for how to do this, using sequential chains. Sequential chains are defined as a series of chains, called in deterministic order. There are two types of sequential chains:\n",
    "\n",
    "- `SimpleSequentialChain`: The simplest form of sequential chains, where each step has a singular input/output, and the output of one step is the input to the next.\n",
    "- `SequentialChain`: A more general form of sequential chains, allowing for multiple inputs/outputs."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5162794e",
   "metadata": {},
   "source": [
    "## SimpleSequentialChain\n",
    "\n",
    "In this series of chains, each individual chain has a single input and a single output, and the output of one step is used as input to the next.\n",
    "\n",
    "Let's walk through a toy example of doing this, where the first chain takes in the title of an imaginary play and then generates a synopsis for that title, and the second chain takes in the synopsis of that play and generates an imaginary review for that play."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "3f2f9b8c",
   "metadata": {},
   "outputs": [],
   "source": [
    "from langchain.llms import OpenAI\n",
    "from langchain.chains import LLMChain\n",
    "from langchain.prompts import PromptTemplate"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "b8237d1a",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is an LLMChain to write a synopsis given a title of a play.\n",
    "llm = OpenAI(temperature=.7)\n",
    "template = \"\"\"You are a playwright. Given the title of play, it is your job to write a synopsis for that title.\n",
    "\n",
    "Title: {title}\n",
    "Playwright: This is a synopsis for the above play:\"\"\"\n",
    "prompt_template = PromptTemplate(input_variables=[\"title\"], template=template)\n",
    "synopsis_chain = LLMChain(llm=llm, prompt=prompt_template)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "4a391730",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is an LLMChain to write a review of a play given a synopsis.\n",
    "llm = OpenAI(temperature=.7)\n",
    "template = \"\"\"You are a play critic from the New York Times. Given the synopsis of play, it is your job to write a review for that play.\n",
    "\n",
    "Play Synopsis:\n",
    "{synopsis}\n",
    "Review from a New York Times play critic of the above play:\"\"\"\n",
    "prompt_template = PromptTemplate(input_variables=[\"synopsis\"], template=template)\n",
    "review_chain = LLMChain(llm=llm, prompt=prompt_template)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "9368bd63",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is the overall chain where we run these two chains in sequence.\n",
    "from langchain.chains import SimpleSequentialChain\n",
    "overall_chain = SimpleSequentialChain(chains=[synopsis_chain, review_chain], verbose=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "d39e15f5",
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   "outputs": [
    {
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     "output_type": "stream",
     "text": [
      "\n",
      "\n",
      "\u001b[1m> Entering new SimpleSequentialChain chain...\u001b[0m\n",
      "\u001b[36;1m\u001b[1;3m\n",
      "\n",
      "Tragedy at Sunset on the Beach follows the story of a young couple, Jack and Annie, who have just started to explore the possibility of a relationship together. After a day spent in the sun and sand, they decide to take a romantic stroll down the beach as the sun sets. \n",
      "\n",
      "However, their romantic evening quickly turns tragic when they stumble upon a body lying in the sand. As they approach to investigate, they are shocked to discover that it is Jack's long-lost brother, who has been missing for several years. \n",
      "\n",
      "The story follows Jack and Annie as they navigate their way through the tragedy and their newfound relationship. With the help of their friends, family, and the beach's inhabitants, Jack and Annie must come to terms with their deep-seated emotions and the reality of the situation. \n",
      "\n",
      "Ultimately, the play explores themes of family, love, and loss, as Jack and Annie's story unfolds against the beautiful backdrop of the beach at sunset.\u001b[0m\n",
      "\u001b[33;1m\u001b[1;3m\n",
      "\n",
      "Tragedy at Sunset on the Beach is an emotionally complex tale of family, love, and loss. Told against the beautiful backdrop of a beach at sunset, the story follows Jack and Annie, a young couple just beginning to explore a relationship together. When they stumble upon the body of Jack's long-lost brother on the beach, they must face the reality of the tragedy and come to terms with their deep-seated emotions. \n",
      "\n",
      "The playwright has crafted a heartfelt and thought-provoking story, one that probes into the depths of the human experience. The cast of characters is well-rounded and fully realized, and the dialogue is natural and emotional. The direction and choreography are top-notch, and the scenic design is breathtaking. \n",
      "\n",
      "Overall, Tragedy at Sunset on the Beach is a powerful and moving story about the fragility of life and the strength of love. It is sure to tug at your heartstrings and leave you with a newfound appreciation of life's precious moments. Highly recommended.\u001b[0m\n",
      "\n",
      "\u001b[1m> Finished SimpleSequentialChain chain.\u001b[0m\n"
     ]
    }
   ],
   "source": [
    "review = overall_chain.run(\"Tragedy at sunset on the beach\")"
   ]
  },
  {
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     "text": [
      "\n",
      "\n",
      "Tragedy at Sunset on the Beach is an emotionally complex tale of family, love, and loss. Told against the beautiful backdrop of a beach at sunset, the story follows Jack and Annie, a young couple just beginning to explore a relationship together. When they stumble upon the body of Jack's long-lost brother on the beach, they must face the reality of the tragedy and come to terms with their deep-seated emotions. \n",
      "\n",
      "The playwright has crafted a heartfelt and thought-provoking story, one that probes into the depths of the human experience. The cast of characters is well-rounded and fully realized, and the dialogue is natural and emotional. The direction and choreography are top-notch, and the scenic design is breathtaking. \n",
      "\n",
      "Overall, Tragedy at Sunset on the Beach is a powerful and moving story about the fragility of life and the strength of love. It is sure to tug at your heartstrings and leave you with a newfound appreciation of life's precious moments. Highly recommended.\n"
     ]
    }
   ],
   "source": [
    "print(review)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "c3f1549a",
   "metadata": {},
   "source": [
    "## Sequential Chain\n",
    "Of course, not all sequential chains will be as simple as passing a single string as an argument and getting a single string as output for all steps in the chain. In this next example, we will experiment with more complex chains that involve multiple inputs, and where there also multiple final outputs. \n",
    "\n",
    "Of particular importance is how we name the input/output variable names. In the above example we didn't have to think about that because we were just passing the output of one chain directly as input to the next, but here we do have worry about that because we have multiple inputs."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "02016a51",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is an LLMChain to write a synopsis given a title of a play and the era it is set in.\n",
    "llm = OpenAI(temperature=.7)\n",
    "template = \"\"\"You are a playwright. Given the title of play and the era it is set in, it is your job to write a synopsis for that title.\n",
    "\n",
    "Title: {title}\n",
    "Era: {era}\n",
    "Playwright: This is a synopsis for the above play:\"\"\"\n",
    "prompt_template = PromptTemplate(input_variables=[\"title\", 'era'], template=template)\n",
    "synopsis_chain = LLMChain(llm=llm, prompt=prompt_template, output_key=\"synopsis\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "8bd38cc2",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is an LLMChain to write a review of a play given a synopsis.\n",
    "llm = OpenAI(temperature=.7)\n",
    "template = \"\"\"You are a play critic from the New York Times. Given the synopsis of play, it is your job to write a review for that play.\n",
    "\n",
    "Play Synopsis:\n",
    "{synopsis}\n",
    "Review from a New York Times play critic of the above play:\"\"\"\n",
    "prompt_template = PromptTemplate(input_variables=[\"synopsis\"], template=template)\n",
    "review_chain = LLMChain(llm=llm, prompt=prompt_template, output_key=\"review\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "524523af",
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is the overall chain where we run these two chains in sequence.\n",
    "from langchain.chains import SequentialChain\n",
    "overall_chain = SequentialChain(\n",
    "    chains=[synopsis_chain, review_chain],\n",
    "    input_variables=[\"era\", \"title\"],\n",
    "    # Here we return multiple variables\n",
    "    output_variables=[\"synopsis\", \"review\"],\n",
    "    verbose=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "3fd3a7be",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "\n",
      "\u001b[1m> Entering new SequentialChain chain...\u001b[0m\n",
      "\u001b[1mChain 0\u001b[0m:\n",
      "{'synopsis': \" \\n\\nTragedy at Sunset on the Beach is a dark and gripping drama set in Victorian England. The play follows the story of two lovers, Emma and Edward, whose passionate relationship is threatened by the strict rules and regulations of the time.\\n\\nThe two are deeply in love, but Edward is from a wealthy family and Emma is from a lower class background. Despite the obstacles, the two are determined to be together and decide to elope.\\n\\nOn the night of their planned escape, Emma and Edward meet at the beach at sunset to declare their love for one another and begin a new life together. However, their plans are disrupted when Emma's father discovers their plan and appears on the beach with a gun.\\n\\nIn a heartbreaking scene, Emma's father orders Edward to leave, but Edward refuses and fights for their love. In a fit of rage, Emma's father shoots Edward, killing him instantly. \\n\\nThe tragedy of the play lies in the fact that Emma and Edward are denied their chance at a happy ending due to the rigid social conventions of Victorian England. The audience is left with a heavy heart as the play ends with Emma standing alone on the beach, mourning the loss of her beloved.\"}\n",
      "\n",
      "\u001b[1mChain 1\u001b[0m:\n",
      "{'review': \"\\n\\nTragedy at Sunset on the Beach is an emotionally charged production that will leave audiences heartsick. The play follows the ill-fated love story of Emma and Edward, two star-crossed lovers whose passionate relationship is tragically thwarted by Victorian England's societal conventions. The performance is captivating from start to finish, as the audience is taken on an emotional rollercoaster of love, loss, and heartbreak.\\n\\nThe acting is powerful and sincere, and the performances of the two leads are particularly stirring. Emma and Edward are both portrayed with such tenderness and emotion that it's hard not to feel their pain as they fight for their forbidden love. The climactic scene, in which Edward is shot by Emma's father, is especially heartbreaking and will leave audience members on the edge of their seats.\\n\\nOverall, Tragedy at Sunset on the Beach is a powerful and moving work of theatre. It is a tragedy of impossible love, and a vivid reminder of the devastating consequences of social injustice. The play is sure to leave a lasting impression on anyone who experiences it.\"}\n",
      "\n",
      "\n",
      "\u001b[1m> Finished SequentialChain chain.\u001b[0m\n"
     ]
    }
   ],
   "source": [
    "review = overall_chain({\"title\":\"Tragedy at sunset on the beach\", \"era\": \"Victorian England\"})"
   ]
  },
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   "execution_count": null,
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