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drc-ners-nlp/pipeline/gender/models/logreg.py
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Python

import os
from dataclasses import dataclass
from typing import Tuple
import pandas as pd
from sklearn.feature_extraction.text import CountVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.metrics import (
accuracy_score, classification_report, confusion_matrix,
precision_recall_fscore_support
)
from sklearn.model_selection import train_test_split, StratifiedKFold, cross_val_score
from sklearn.pipeline import make_pipeline, Pipeline
from sklearn.preprocessing import LabelEncoder
from misc import GENDER_MODELS_DIR, load_csv_dataset, save_pickle
from pipeline.gender.models import BaseConfig, load_config, logging
@dataclass
class Config(BaseConfig):
ngram_range: Tuple[int, int] = (2, 5)
max_iter: int = 1000
def encode_labels(y: pd.Series) -> Tuple[pd.Series, LabelEncoder]:
"""
Encode the labels using a LabelEncoder. This function takes a pandas Series of labels,
fits a LabelEncoder to the labels, and transforms them into a numerical format suitable
for model training. The transformed labels and the fitted encoder are returned.
"""
logging.info("Encoding labels")
encoder = LabelEncoder()
y_encoded = encoder.fit_transform(y)
return y_encoded, encoder
def build_model(cfg: Config) -> Pipeline:
"""
Build a logistic regression model pipeline with a character-level CountVectorizer.
The pipeline consists of a CountVectorizer that transforms the input text into
character n-grams, followed by a Logistic Regression classifier. The n-gram range
and maximum iterations for the logistic regression can be configured through the
provided configuration object.
"""
return make_pipeline(
CountVectorizer(analyzer="char", ngram_range=cfg.ngram_range),
LogisticRegression(max_iter=cfg.max_iter)
)
def evaluate_proba(y_true, y_proba, threshold: float, class_names):
"""
Evaluates the performance of a classification model using a specified threshold
for predicted probabilities. Computes metrics such as accuracy, precision,
recall, F1-score, and the confusion matrix. Also generates a classification
report with detailed metrics for each class.
Logs the evaluation metrics at the specified threshold and prints the confusion
matrix and classification report.
"""
logging.info(f"Evaluating at threshold = {threshold}")
y_pred = (y_proba[:, 1] >= threshold).astype(int)
acc = accuracy_score(y_true, y_pred)
pr, rc, f1, _ = precision_recall_fscore_support(y_true, y_pred, average='binary')
cm = confusion_matrix(y_true, y_pred)
logging.info(f"Accuracy: {acc:.4f}")
logging.info(f"Precision: {pr:.4f}, Recall: {rc:.4f}, F1-score: {f1:.4f}")
print("Confusion Matrix:\n", cm)
print("\nClassification Report:\n", classification_report(y_true, y_pred, target_names=class_names))
def cross_validate(cfg: Config, X, y) -> None:
"""
Performs k-fold cross-validation on the provided dataset using the configuration and
logs the results including individual fold scores, mean accuracy, and the standard
deviation of the scores.
"""
logging.info(f"Running {cfg.cv}-fold cross-validation")
pipeline = build_model(cfg)
scores = cross_val_score(pipeline, X, y, cv=StratifiedKFold(n_splits=cfg.cv), scoring="accuracy")
logging.info(f"Cross-validation scores: {scores}")
logging.info(f"Mean accuracy: {scores.mean():.4f}, Std: {scores.std():.4f}")
def save_artifacts(model, encoder):
"""
Saves the trained model and label encoder artifacts to the specified directory.
"""
save_pickle(model, os.path.join(GENDER_MODELS_DIR, "regression_model.pkl"))
save_pickle(encoder, os.path.join(GENDER_MODELS_DIR, "regression_label_encoder.pkl"))
logging.info(f"Model and artifacts saved to {GENDER_MODELS_DIR}")
def main():
cfg = Config(**vars(load_config("logistic regression model")))
df = pd.DataFrame(load_csv_dataset(cfg.dataset_path, cfg.size, cfg.balanced))
X_raw, y_raw = df["name"], df["sex"]
y_encoded, encoder = encode_labels(y_raw)
if cfg.cv:
cross_validate(cfg, X_raw, y_encoded)
return
X_train, X_test, y_train, y_test = train_test_split(
X_raw, y_encoded, test_size=cfg.test_size, random_state=cfg.random_state, stratify=y_encoded
)
model = build_model(cfg)
model.fit(X_train, y_train)
y_proba = model.predict_proba(X_test)
evaluate_proba(y_test, y_proba, cfg.threshold, class_names=encoder.classes_)
if cfg.save:
save_artifacts(model, encoder)
if __name__ == "__main__":
main()