This tutorial guides you through the essential steps to install the plexe library, define a model using natural language, build it using your data, and make predictions.

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1. Installation

First, install the plexe library using pip. You can choose between a standard installation, a lightweight version (without deep learning dependencies), or include all optional dependencies. 
pip install plexe

pip install plexe[lightweight]

pip install plexe[all]

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2. Set Up Environment Variables

Plexe uses Large Language Models (LLMs) under the hood via the LiteLLM library. You need to configure API keys for the LLM provider you want to use. Set them as environment variables: 
# Example for OpenAI
export OPENAI_API_KEY="YOUR_OPENAI_API_KEY"

# Example for Anthropic
# export ANTHROPIC_API_KEY="YOUR_ANTHROPIC_API_KEY"
Plexe defaults to openai/gpt-4o-mini if no provider is specified.

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3. Prepare Your Data

For this example, let’s assume you have a CSV file named housing_data.csv with features like square_footage, bedrooms, bathrooms, and a target column price. 
import pandas as pd

# Load your data (replace with your actual data loading)
try:
    df = pd.read_csv("housing_data.csv")
    print("Dataset loaded successfully:")
    print(df.head())
except FileNotFoundError:
    print("Error: housing_data.csv not found. Please create a sample CSV.")
    # Create a dummy DataFrame for demonstration if file not found
    df = pd.DataFrame({
        'square_footage': [1500, 2100, 1800, 2500, 1200],
        'bedrooms': [3, 4, 3, 5, 2],
        'bathrooms': [2, 2.5, 2, 3, 1.5],
        'price': [300000, 450000, 380000, 550000, 250000]
    })
    print("Using dummy data:")
    print(df.head())

# Ensure your DataFrame is ready
datasets = [df]

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4. Define and Build the Model

Import the plexe library and create a Model instance. Define your goal using the intent parameter. You can also specify input and output schemas, though Plexe can often infer them. 
import plexe
import logging

# Optional: Configure logging for more details
# plexe.configure_logging(level=logging.DEBUG)

# Define the model's intent
# Input and output schemas can often be inferred if data is provided
model = plexe.Model(
    intent="Predict house prices based on square footage, bedrooms, and bathrooms."
    # Optionally define schemas:
    # input_schema={"square_footage": float, "bedrooms": int, "bathrooms": float},
    # output_schema={"price": float}
)

# Build the model
# This process involves LLM calls, code generation, and execution.
# It might take a few minutes depending on complexity and provider.
print("Starting model build...")
model.build(
    datasets=datasets,
    provider="openai/gpt-4o-mini", # Specify your preferred LLM provider
    max_iterations=5,              # Try up to 5 different model approaches
    timeout=600,                   # Set a maximum of 10 minutes for the entire process
    run_timeout=180,               # Maximum 3 minutes per individual run
    chain_of_thought=True,         # Show detailed reasoning steps (default: True)
    verbose=False                  # Don't show detailed agent logs (default: False)
)

print(f"Model build finished. Model state: {model.get_state()}")
The build process involves multiple steps orchestrated by AI agents: planning, code generation, execution, analysis, and potentially fixing code. Enabling chain_of_thought=True provides verbose output showing these steps.

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5. Make Predictions

Once the model state is READY, you can use the predict method. 
if model.get_state() == "ready":
    # Prepare input data as a dictionary
    input_data = {
        "square_footage": 1900.0,
        "bedrooms": 3,
        "bathrooms": 2.0
    }

    print(f"\nMaking prediction for input: {input_data}")
    prediction = model.predict(input_data)
    print(f"Predicted price: {prediction}")

    # Example with validation
    # prediction_validated = model.predict(input_data, validate_input=True, validate_output=True)
    # print(f"Validated prediction: {prediction_validated}")

else:
    print("\nModel is not ready for prediction. Check logs for errors.")

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6. Inspect the Model

You can get metadata and a description of the built model. 
if model.get_state() == "ready":
    print("\nModel Metadata:")
    print(model.get_metadata())

    print("\nModel Metrics:")
    print(model.get_metrics())

    print("\nModel Description:")
    # The describe() method returns a detailed object, print its text representation
    print(model.describe().as_text())
    # Or use as_markdown() or to_dict() / to_json()
    # print(model.describe().as_markdown())
else:
    print("\nModel information not available as it's not in READY state.")

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7. Save and Load (Optional)

Persist your trained model for later use. 
import os

if model.get_state() == "ready":
    model_filename = f"{model.identifier}.tar.gz"
    save_path = plexe.save_model(model, model_filename)
    print(f"\nModel saved to: {save_path}")

    # Load the model later
    if os.path.exists(save_path):
      loaded_model = plexe.load_model(save_path)
      print(f"Model loaded successfully. Intent: {loaded_model.intent}")
      # You can now use loaded_model.predict()
    else:
        print("Saved model file not found for loading example.")
That’s it! You’ve built, trained, and used a machine learning model using natural language with the plexe library. Explore the other tutorials and guides to learn about more advanced features.