Templates (#12294)

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>
Co-authored-by: Lance Martin <lance@langchain.dev>
Co-authored-by: Jacob Lee <jacoblee93@gmail.com>

templates/rewrite-retrieve-read/rewrite_retrieve_read/chain.py

@@ -0,0 +1,43 @@
+from operator import itemgetter
+
+from langchain.prompts import ChatPromptTemplate
+from langchain.chat_models import ChatOpenAI
+from langchain.schema.output_parser import StrOutputParser
+from langchain.schema.runnable import RunnablePassthrough, RunnableLambda
+from langchain.utilities import DuckDuckGoSearchAPIWrapper
+
+template = """Answer the users question based only on the following context:
+
+<context>
+{context}
+</context>
+
+Question: {question}
+"""
+prompt = ChatPromptTemplate.from_template(template)
+
+model = ChatOpenAI(temperature=0)
+
+search = DuckDuckGoSearchAPIWrapper()
+
+
+def retriever(query):
+    return search.run(query)
+
+template = """Provide a better search query for \
+web search engine to answer the given question, end \
+the queries with ’**’. Question: \
+{x} Answer:"""
+rewrite_prompt = ChatPromptTemplate.from_template(template)
+
+# Parser to remove the `**`
+
+def _parse(text):
+    return text.strip("**")
+
+rewriter = rewrite_prompt | ChatOpenAI(temperature=0) | StrOutputParser() | _parse
+
+chain = {
+    "context": {"x": RunnablePassthrough()} | rewriter | retriever,
+    "question": RunnablePassthrough()
+    } | prompt | model | StrOutputParser()