app.py

from __future__ import annotations

from pathlib import Path

import gradio as gr
import joblib
import pandas as pd


ARTIFACT_PATH = Path(__file__).with_name("model.joblib")


def _load_bundle() -> dict:
    if not ARTIFACT_PATH.exists():
        from train import train_and_save

        train_and_save(ARTIFACT_PATH)

    return joblib.load(ARTIFACT_PATH)


BUNDLE = _load_bundle()
MODEL = BUNDLE["model"]
TARGET_NAMES = BUNDLE["target_names"]
FEATURE_NAMES = BUNDLE["feature_names"]


def predict(sepal_length: float, sepal_width: float, petal_length: float, petal_width: float):
    x = pd.DataFrame(
        [[sepal_length, sepal_width, petal_length, petal_width]],
        columns=FEATURE_NAMES,
    )

    pred_idx = int(MODEL.predict(x)[0])
    pred_label = TARGET_NAMES[pred_idx]

    if hasattr(MODEL, "predict_proba"):
        proba = MODEL.predict_proba(x)[0]
        proba_dict = {str(TARGET_NAMES[i]): float(proba[i]) for i in range(len(TARGET_NAMES))}
    else:
        proba_dict = {TARGET_NAMES[pred_idx]: 1.0}

    return pred_label, proba_dict


demo = gr.Interface(
    fn=predict,
    inputs=[
        gr.Number(label=FEATURE_NAMES[0], value=5.8),
        gr.Number(label=FEATURE_NAMES[1], value=3.0),
        gr.Number(label=FEATURE_NAMES[2], value=4.0),
        gr.Number(label=FEATURE_NAMES[3], value=1.2),
    ],
    outputs=[
        gr.Textbox(label="Predicted class"),
        gr.Label(label="Class probabilities"),
    ],
    title="Iris Classification (KNN)",
    description=(
        "KNN classifier trained on the classic Iris dataset. "
        "Enter measurements and get a predicted species + probabilities."
    ),
)


if __name__ == "__main__":
    demo.launch()