src/evaluate.py

# /// script
# requires-python = ">=3.9"
# dependencies = [
#     "python-crfsuite>=0.9.11",
#     "datasets>=4.5.0",
#     "scikit-learn>=1.6.1",
#     "matplotlib>=3.5.0",
#     "seaborn>=0.12.0",
#     "click>=8.0.0",
# ]
# ///
"""
Evaluation script for Vietnamese POS Tagger (TRE-1).

Usage:
    uv run scripts/evaluate.py
    uv run scripts/evaluate.py --version v1.0.0
    uv run scripts/evaluate.py --model models/pos_tagger/v1.0.0/model.crfsuite
    uv run scripts/evaluate.py --save-plots
"""

import re
from collections import Counter
from pathlib import Path

import click
import pycrfsuite
from datasets import load_dataset

# Get project root directory
PROJECT_ROOT = Path(__file__).parent.parent
from sklearn.metrics import (
    accuracy_score,
    precision_recall_fscore_support,
    classification_report,
    confusion_matrix,
)


FEATURE_TEMPLATES = [
    "T[0]", "T[0].lower", "T[0].istitle", "T[0].isupper",
    "T[0].isdigit", "T[0].isalpha", "T[0].prefix2", "T[0].prefix3",
    "T[0].suffix2", "T[0].suffix3", "T[-1]", "T[-1].lower",
    "T[-1].istitle", "T[-1].isupper", "T[-2]", "T[-2].lower",
    "T[1]", "T[1].lower", "T[1].istitle", "T[1].isupper",
    "T[2]", "T[2].lower", "T[-1,0]", "T[0,1]",
    "T[0].is_in_dict", "T[-1,0].is_in_dict", "T[0,1].is_in_dict",
]


def get_token_value(tokens, position, index):
    actual_pos = position + index
    if actual_pos < 0:
        return "__BOS__"
    elif actual_pos >= len(tokens):
        return "__EOS__"
    return tokens[actual_pos]


def apply_attribute(value, attribute, dictionary=None):
    if value in ("__BOS__", "__EOS__"):
        return value
    if attribute is None:
        return value
    elif attribute == "lower":
        return value.lower()
    elif attribute == "upper":
        return value.upper()
    elif attribute == "istitle":
        return str(value.istitle())
    elif attribute == "isupper":
        return str(value.isupper())
    elif attribute == "islower":
        return str(value.islower())
    elif attribute == "isdigit":
        return str(value.isdigit())
    elif attribute == "isalpha":
        return str(value.isalpha())
    elif attribute == "is_in_dict":
        return str(value in dictionary) if dictionary else "False"
    elif attribute.startswith("prefix"):
        n = int(attribute[6:]) if len(attribute) > 6 else 2
        return value[:n] if len(value) >= n else value
    elif attribute.startswith("suffix"):
        n = int(attribute[6:]) if len(attribute) > 6 else 2
        return value[-n:] if len(value) >= n else value
    return value


def parse_template(template):
    match = re.match(r"T\[([^\]]+)\](?:\.(\w+))?", template)
    if not match:
        return None, None
    indices_str = match.group(1)
    attribute = match.group(2)
    indices = [int(i.strip()) for i in indices_str.split(",")]
    return indices, attribute


def extract_features(tokens, position, dictionary=None):
    features = {}
    for template in FEATURE_TEMPLATES:
        indices, attribute = parse_template(template)
        if indices is None:
            continue
        if len(indices) == 1:
            value = get_token_value(tokens, position, indices[0])
            value = apply_attribute(value, attribute, dictionary)
            features[template] = value
        else:
            values = [get_token_value(tokens, position, idx) for idx in indices]
            if attribute == "is_in_dict":
                combined = " ".join(values)
                features[template] = str(combined in dictionary) if dictionary else "False"
            else:
                combined = "|".join(values)
                features[template] = combined
    return features


def sentence_to_features(tokens):
    return [
        [f"{k}={v}" for k, v in extract_features(tokens, i).items()]
        for i in range(len(tokens))
    ]


def load_test_data():
    click.echo("Loading UDD-1 dataset...")
    dataset = load_dataset("undertheseanlp/UDD-1")

    sentences = []
    for item in dataset["test"]:
        tokens = item["tokens"]
        tags = item["upos"]
        if tokens and tags:
            sentences.append((tokens, tags))

    click.echo(f"Test set: {len(sentences)} sentences")
    return sentences


def plot_confusion_matrix(y_true, y_pred, labels, output_path):
    import matplotlib.pyplot as plt
    import seaborn as sns

    cm = confusion_matrix(y_true, y_pred, labels=labels)

    plt.figure(figsize=(12, 10))
    sns.heatmap(
        cm,
        annot=True,
        fmt="d",
        cmap="Blues",
        xticklabels=labels,
        yticklabels=labels,
    )
    plt.xlabel("Predicted")
    plt.ylabel("True")
    plt.title("Confusion Matrix - Vietnamese POS Tagger (TRE-1)")
    plt.tight_layout()
    plt.savefig(output_path, dpi=150)
    plt.close()
    click.echo(f"Confusion matrix saved to {output_path}")


def plot_per_tag_metrics(report_dict, output_path):
    import matplotlib.pyplot as plt

    tags = [k for k in report_dict.keys() if k not in ("accuracy", "macro avg", "weighted avg")]

    precision = [report_dict[t]["precision"] for t in tags]
    recall = [report_dict[t]["recall"] for t in tags]
    f1 = [report_dict[t]["f1-score"] for t in tags]

    x = range(len(tags))
    width = 0.25

    fig, ax = plt.subplots(figsize=(14, 6))
    ax.bar([i - width for i in x], precision, width, label="Precision", color="#2ecc71")
    ax.bar(x, recall, width, label="Recall", color="#3498db")
    ax.bar([i + width for i in x], f1, width, label="F1-Score", color="#e74c3c")

    ax.set_xlabel("POS Tag")
    ax.set_ylabel("Score")
    ax.set_title("Per-Tag Performance Metrics - Vietnamese POS Tagger (TRE-1)")
    ax.set_xticks(x)
    ax.set_xticklabels(tags, rotation=45)
    ax.legend()
    ax.set_ylim(0, 1.1)
    ax.grid(axis="y", alpha=0.3)

    plt.tight_layout()
    plt.savefig(output_path, dpi=150)
    plt.close()
    click.echo(f"Per-tag metrics saved to {output_path}")


def analyze_errors(y_true, y_pred, tokens_flat, top_n=10):
    """Analyze common error patterns."""
    errors = Counter()
    error_examples = {}

    for true, pred, token in zip(y_true, y_pred, tokens_flat):
        if true != pred:
            key = (true, pred)
            errors[key] += 1
            if key not in error_examples:
                error_examples[key] = token

    click.echo(f"\nTop {top_n} Error Patterns:")
    click.echo("-" * 60)
    click.echo(f"{'True':<10} {'Predicted':<10} {'Count':<8} {'Example'}")
    click.echo("-" * 60)

    for (true, pred), count in errors.most_common(top_n):
        example = error_examples.get((true, pred), "")
        click.echo(f"{true:<10} {pred:<10} {count:<8} {example}")


def get_latest_version(task="pos_tagger"):
    """Get the latest model version (sorted by timestamp)."""
    models_dir = PROJECT_ROOT / "models" / task
    if not models_dir.exists():
        return None
    versions = [d.name for d in models_dir.iterdir() if d.is_dir()]
    if not versions:
        return None
    return sorted(versions)[-1]  # Latest timestamp


@click.command()
@click.option(
    "--version", "-v",
    default=None,
    help="Model version to evaluate (default: latest)",
)
@click.option(
    "--model", "-m",
    default=None,
    help="Custom model path (overrides version-based path)",
)
@click.option(
    "--save-plots",
    is_flag=True,
    help="Save confusion matrix and per-tag metrics plots",
)
def evaluate(version, model, save_plots):
    """Evaluate Vietnamese POS Tagger on UDD-1 test set."""
    # Use latest version if not specified
    if version is None and model is None:
        version = get_latest_version("pos_tagger")
        if version is None:
            raise click.ClickException("No models found in models/pos_tagger/")

    # Determine model path
    if model:
        model_path = Path(model)
    else:
        model_path = PROJECT_ROOT / "models" / "pos_tagger" / version / "model.crfsuite"

    # Determine output directory for plots
    if save_plots:
        results_dir = PROJECT_ROOT / "results" / "pos_tagger"
        results_dir.mkdir(parents=True, exist_ok=True)

    click.echo(f"Loading model from {model_path}...")
    tagger = pycrfsuite.Tagger()
    tagger.open(str(model_path))

    test_data = load_test_data()

    click.echo("Extracting features and predicting...")
    X_test = [sentence_to_features(tokens) for tokens, _ in test_data]
    y_test = [tags for _, tags in test_data]
    tokens_test = [tokens for tokens, _ in test_data]

    y_pred = [tagger.tag(xseq) for xseq in X_test]

    # Flatten
    y_test_flat = [tag for tags in y_test for tag in tags]
    y_pred_flat = [tag for tags in y_pred for tag in tags]
    tokens_flat = [token for tokens in tokens_test for token in tokens]

    # Get unique labels
    labels = sorted(set(y_test_flat))

    # Overall metrics
    accuracy = accuracy_score(y_test_flat, y_pred_flat)
    precision_macro, recall_macro, f1_macro, _ = precision_recall_fscore_support(
        y_test_flat, y_pred_flat, average="macro"
    )
    _, _, f1_weighted, _ = precision_recall_fscore_support(
        y_test_flat, y_pred_flat, average="weighted"
    )

    click.echo("\n" + "=" * 60)
    click.echo("EVALUATION RESULTS")
    click.echo("=" * 60)

    click.echo("\nOverall Metrics:")
    click.echo(f"  Accuracy:           {accuracy:.4f} ({accuracy*100:.2f}%)")
    click.echo(f"  Precision (macro):  {precision_macro:.4f}")
    click.echo(f"  Recall (macro):     {recall_macro:.4f}")
    click.echo(f"  F1 (macro):         {f1_macro:.4f}")
    click.echo(f"  F1 (weighted):      {f1_weighted:.4f}")

    click.echo("\nPer-Tag Classification Report:")
    report = classification_report(y_test_flat, y_pred_flat, digits=4)
    click.echo(report)

    # Error analysis
    analyze_errors(y_test_flat, y_pred_flat, tokens_flat)

    # Dataset statistics
    tag_counts = Counter(y_test_flat)
    total_tokens = len(y_test_flat)

    click.echo("\nTest Set Tag Distribution:")
    click.echo("-" * 40)
    for tag in labels:
        count = tag_counts[tag]
        pct = count / total_tokens * 100
        click.echo(f"  {tag:<8} {count:>6} ({pct:>5.2f}%)")

    if save_plots:
        cm_path = results_dir / f"confusion_matrix_{version}.png"
        plot_confusion_matrix(
            y_test_flat, y_pred_flat, labels,
            str(cm_path)
        )

        report_dict = classification_report(
            y_test_flat, y_pred_flat, output_dict=True
        )
        metrics_path = results_dir / f"per_tag_metrics_{version}.png"
        plot_per_tag_metrics(report_dict, str(metrics_path))

    return accuracy


if __name__ == "__main__":
    evaluate()