06. Date format output parser (DatetimeOutputParser)

DatetimeOutputParser

DatetimeOutputParser can be used to parse the output of LLM into datetime format.

from dotenv import load_dotenv

load_dotenv()

True

# Set up LangSmith tracking. https://smith.langchain.com
# !pip install langchain-teddynote
from langchain_teddynote import logging

# Enter a project name.
logging.langsmith("CH03-OutputParser")

Start tracking LangSmith.
[project name]
CH03-OutputParser

reference

Format code	Explaination	Example
%Y	4 digit year	2024
%y	2 digit year	24
%m	2 digit month	07
%d	2 digit day	04
%H	24 hour clock	14
%I	12-hour clock	02
%p	AM or PM	PM
%M	2 digits	45
%S	2 digit seconds	08
%f	Microseconds (6 digits)	000123
%z	UTC offset	+0900
%Z	Time zone name	KST
%a	Day of the week abbreviation	Thu
%A	All days of the week	Thursday
%b	Month Abbreviation	Jul
%B	Whole month	July
%c	Full date and time	Thu Jul 4 14:45:08 2024
%x	Full date	07/04/24
%X	Total time	14:45:08

from langchain.output_parsers import DatetimeOutputParser
from langchain.prompts import PromptTemplate
from langchain_openai import ChatOpenAI

# Date and time output parser
output_parser = DatetimeOutputParser()
output_parser.format = "%Y-%m-%d"

# Template for answering user questions
template = """Answer the users question:\n\n#Format Instructions: \n{format_instructions}\n\n#Question: \n{question}\n\n#Answer:"""

prompt = PromptTemplate.from_template(
    template,
    partial_variables={
        "format_instructions": output_parser.get_format_instructions()
    },  Apply the instructions to the template

)

# Print the prompt contents
prompt

PromptTemplate(input_variables=['question'], partial_variables={'format_instructions': "Write a datetime string that matches the following pattern: '%Y-%m-%d'.\n\nExamples: 0751-08-07, 0937-04-06, 0298-07-15\n\nReturn ONLY this string, no other words!"}, template='Answer the users question:\n\n#Format Instructions: \n{format_instructions}\n\n#Question: \n{question}\n\n#Answer:')

Create a chain.

# Chain creates.
chain = prompt | ChatOpenAI() | output_parser

# Call the chain to get answers to your questions.
output = chain.invoke({"question": "Google 이 창업한 연도는?"})

Prints the results.

# Convert result to string
output.strftime("%Y-%m-%d")

'1998-09-04'