src/models/train_compare_models.py

import os
import mlflow
import mlflow.sklearn
import pandas as pd
import joblib

from sklearn.pipeline import Pipeline
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.svm import LinearSVC
from sklearn.ensemble import RandomForestClassifier
from sklearn.metrics import accuracy_score, f1_score, classification_report


train_df = pd.read_csv("data/splits/train.csv")
val_df = pd.read_csv("data/splits/val.csv")

X_train = train_df["clean_text"]
y_train = train_df["label_text"]

X_val = val_df["clean_text"]
y_val = val_df["label_text"]

os.makedirs("models", exist_ok=True)

models = {
    "logistic_regression": LogisticRegression(max_iter=1000),
    "linear_svm": LinearSVC(),
    "random_forest": RandomForestClassifier(n_estimators=100, random_state=42),
}

mlflow.set_experiment("bbc-document-classification")

best_model = None
best_model_name = None
best_f1 = 0

for model_name, classifier in models.items():
    with mlflow.start_run(run_name=model_name):

        pipeline = Pipeline([
            ("tfidf", TfidfVectorizer(max_features=5000)),
            ("classifier", classifier)
        ])

        pipeline.fit(X_train, y_train)

        y_pred = pipeline.predict(X_val)

        accuracy = accuracy_score(y_val, y_pred)
        f1 = f1_score(y_val, y_pred, average="weighted")

        print("\n==============================")
        print(f"Model: {model_name}")
        print("Accuracy:", accuracy)
        print("F1 Score:", f1)
        print(classification_report(y_val, y_pred))

        mlflow.log_param("model_name", model_name)
        mlflow.log_param("vectorizer", "TF-IDF")
        mlflow.log_param("max_features", 5000)
        mlflow.log_metric("accuracy", accuracy)
        mlflow.log_metric("f1_score", f1)

        mlflow.sklearn.log_model(pipeline, model_name)

        if f1 > best_f1:
            best_f1 = f1
            best_model = pipeline
            best_model_name = model_name

joblib.dump(best_model, "models/best_model.pkl")

print("\nBest model:", best_model_name)
print("Best F1:", best_f1)
print("Saved to models/best_model.pkl")