Example: Text Classification using OpenAI and Pydantic¶
This tutorial showcases how to implement text classification tasks—specifically, single-label and multi-label classifications—using the OpenAI API, Python's enum module, and Pydantic models.
Motivation
Text classification is a common problem in many NLP applications, such as spam detection or support ticket categorization. The goal is to provide a systematic way to handle these cases using OpenAI's GPT models in combination with Python data structures.
Single-Label Classification¶
Defining the Structures¶
For single-label classification, we first define an enum for possible labels and a Pydantic model for the output.
import enum
from pydantic import BaseModel
class Labels(str, enum.Enum):
"""Enumeration for single-label text classification."""
SPAM = "spam"
NOT_SPAM = "not_spam"
class SinglePrediction(BaseModel):
"""
Class for a single class label prediction.
"""
class_label: Labels
Classifying Text¶
The function classify will perform the single-label classification.
from openai import OpenAI
import instructor
# Apply the patch to the OpenAI client
# enables response_model keyword
client = instructor.from_openai(OpenAI())
def classify(data: str) -> SinglePrediction:
"""Perform single-label classification on the input text."""
return client.chat.completions.create(
model="gpt-3.5-turbo-0613",
response_model=SinglePrediction,
messages=[
{
"role": "user",
"content": f"Classify the following text: {data}",
},
],
) # type: ignore
Testing and Evaluation¶
Let's run an example to see if it correctly identifies a spam message.
# Test single-label classification
prediction = classify("Hello there I'm a Nigerian prince and I want to give you money")
assert prediction.class_label == Labels.SPAM
Multi-Label Classification¶
Defining the Structures¶
For multi-label classification, we introduce a new enum class and a different Pydantic model to handle multiple labels.
from typing import List
import enum
# Define Enum class for multiple labels
class MultiLabels(str, enum.Enum):
TECH_ISSUE = "tech_issue"
BILLING = "billing"
GENERAL_QUERY = "general_query"
# Define the multi-class prediction model
class MultiClassPrediction(BaseModel):
"""
Class for a multi-class label prediction.
"""
class_labels: List[MultiLabels]
Classifying Text¶
The function multi_classify is responsible for multi-label classification.
def multi_classify(data: str) -> MultiClassPrediction:
"""Perform multi-label classification on the input text."""
return client.chat.completions.create(
model="gpt-3.5-turbo-0613",
response_model=MultiClassPrediction,
messages=[
{
"role": "user",
"content": f"Classify the following support ticket: {data}",
},
],
) # type: ignore
Testing and Evaluation¶
Finally, we test the multi-label classification function using a sample support ticket.