Example of function calling using OpenAI in Python

function_call_example.py

# Example of function call using OpenAI
# by Enrico Zimuel (https://github.com/ezimuel)
#
# To run the code you need the OPENAI_API_KEY as env variable
# For more information: https://platform.openai.com/docs/guides/function-calling?api-mode=chat

from openai import OpenAI
import requests
import json
import datetime

def get_weather(location: str)-> str:
    """
    Get current temperature for a given location.

    Args:
        location (str): City and country e.g. Rome, Italy
    """
    # Get the latitude, longitude for the location
    response = requests.get(f"https://geocoding-api.open-meteo.com/v1/search?name={location}&number=1")
    data = response.json()
    lat, lon = (data['results'][0]['latitude'], data['results'][0]['longitude'])
    # Get current date and hour
    now = datetime.datetime.now()
    date = now.strftime("%Y-%m-%d")
    hour = int(now.strftime("%H"))
    # Get the temperature for today
    response = requests.get(f"https://api.open-meteo.com/v1/forecast?latitude={lat}&longitude={lon}&hourly=temperature_2m&start_date={date}&end_date={date}")
    data = response.json()

    return f"{data['hourly']['temperature_2m'][hour]} °C"

client = OpenAI()
tools = [{
    "type": "function",
    "function": {
        "name": "get_weather",
        "description": "Get current temperature for a given location.",
        "parameters": {
            "type": "object",
            "properties": {
                "location": {
                    "type": "string",
                    "description": "City and country e.g. Rome, Italy"
                }
            },
            "required": [
                "location"
            ],
            "additionalProperties": False
        },
        "strict": True
    }
}]
messages = [{
    "role": "user", 
    "content": "What's the temperature now in Milan?"
}]
response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=messages,
    tools=tools
)

tool_call = response.choices[0].message.tool_calls[0]
kwargs = json.loads(tool_call.function.arguments)

# Execute the function
content = get_weather(**kwargs)
print(f"Response from get_weather(): {content}")

# append the previous function call message
messages.append(response.choices[0].message)
# append result message
messages.append({
    "role": "tool",
    "tool_call_id": tool_call.id,
    "content": content
})

response2 = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=messages,
    tools=tools,
)
print(f"Response from LLM: {response2.choices[0].message.content}")