CommaSeparatedListOutputParser in LangChain - Mini Project: Build & Apply

Using CommaSeparatedListOutputParser in Langchain

📖 Scenario: You are building a chatbot that extracts a list of fruits from user input. The chatbot should return the fruits as a clean list separated by commas.

🎯 Goal: Create a Langchain output parser called CommaSeparatedListOutputParser that processes a string of fruits separated by commas and returns a Python list of fruit names.

📋 What You'll Learn

Create a variable named raw_output with a string of fruits separated by commas

Create a variable named parser that is an instance of CommaSeparatedListOutputParser

Use the parse method of parser to convert raw_output into a list called fruit_list

Print the fruit_list to verify it contains the fruits as a Python list

💡 Why This Matters

🌍 Real World

Many chatbots and AI applications need to extract lists from text responses. This parser helps convert comma-separated text into usable Python lists.

💼 Career

Understanding how to parse and process text outputs is important for AI developers, data engineers, and software developers working with language models.

1

Create the raw output string

Create a variable called raw_output and set it to the string "apple, banana, cherry, date".

LangChain

# Create a variable called raw_output with the string "apple, banana, cherry, date"
# Your code here

Need a hint?

Use quotes to create a string with the fruits separated by commas.

2

Create the CommaSeparatedListOutputParser instance

Create a variable called parser and set it to an instance of CommaSeparatedListOutputParser().

LangChain

raw_output = "apple, banana, cherry, date"
# Create a variable called parser as CommaSeparatedListOutputParser()
# Your code here

Need a hint?

Import CommaSeparatedListOutputParser from langchain.output_parsers and create an instance.

3

Parse the raw output into a list

Use the parse method of parser to convert raw_output into a list called fruit_list.

LangChain

raw_output = "apple, banana, cherry, date"
from langchain.output_parsers import CommaSeparatedListOutputParser
parser = CommaSeparatedListOutputParser()
# Use parser.parse(raw_output) to create fruit_list
# Your code here

Need a hint?

Call parser.parse(raw_output) and assign it to fruit_list.

4

Print the parsed fruit list

Add a line to print the variable fruit_list to verify it contains the list of fruits.

LangChain

raw_output = "apple, banana, cherry, date"
from langchain.output_parsers import CommaSeparatedListOutputParser
parser = CommaSeparatedListOutputParser()
fruit_list = parser.parse(raw_output)
# Print fruit_list
# Your code here

Need a hint?

Use print(fruit_list) to show the list of fruits.