Compare multiple test conditions on the same time axis

python --version
python -m pip install -r requirements.txt
python example.py

"""Overlay explanatory synthetic test conditions on the same axes.

All files must have the same explicit units and matching time samples.
No interpolation, clock shifting, filtering, or safety assessment is performed.
"""
import csv
import math
from pathlib import Path

import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt

BASE = Path(__file__).resolve().parent
HEADERS = ["dataset_note", "condition", "time", "time_unit", "acceleration", "acceleration_unit"]
NOTE = "설명용 합성 데이터"


def read_condition(path):
    times, values = [], []
    label = None
    with path.open(encoding="utf-8-sig", newline="") as file:
        reader = csv.DictReader(file)
        if reader.fieldnames != HEADERS:
            raise ValueError(f"{path.name}: expected headers {HEADERS}")
        for line, row in enumerate(reader, start=2):
            if None in row or any(value is None or not value.strip() for value in row.values()):
                raise ValueError(f"{path.name}:{line}: missing or extra field.")
            if row["dataset_note"] != NOTE:
                raise ValueError(f"{path.name}:{line}: synthetic-data label is required.")
            if row["time_unit"] != "s" or row["acceleration_unit"] != "m/s^2":
                raise ValueError(f"{path.name}:{line}: expected units s and m/s^2; no automatic conversion.")
            if not row["condition"].isascii():
                raise ValueError(f"{path.name}:{line}: use an ASCII condition label for portable plotting.")
            label = row["condition"] if label is None else label
            if row["condition"] != label:
                raise ValueError(f"{path.name}:{line}: condition label changes within one file.")
            time, value = float(row["time"]), float(row["acceleration"])
            if not math.isfinite(time) or not math.isfinite(value) or time < 0:
                raise ValueError(f"{path.name}:{line}: expected finite values and nonnegative time.")
            if times and time <= times[-1]:
                raise ValueError(f"{path.name}:{line}: duplicate or decreasing time.")
            times.append(time)
            values.append(value)
    if len(times) < 2:
        raise ValueError(f"{path.name}: at least two samples are required.")
    return label, times, values


def main():
    destination = BASE / "outputs"
    if destination.exists():
        raise ValueError("outputs already exists; rename it before running again.")
    paths = sorted((BASE / "inputs").glob("*.csv"))
    if len(paths) < 2:
        raise ValueError("At least two CSV files are required in inputs.")
    conditions = [read_condition(path) for path in paths]
    if len({label for label, _, _ in conditions}) != len(conditions):
        raise ValueError("Condition labels must be unique across files.")
    reference_times = conditions[0][1]
    if any(times != reference_times for _, times, _ in conditions[1:]):
        raise ValueError("Time samples do not match; check alignment before comparison.")

    figure, axis = plt.subplots(figsize=(8, 4.6), layout="constrained")
    for label, times, values in conditions:
        axis.plot(times, values, marker="o", linewidth=2, label=label)
    axis.set(title="Test conditions | Explanatory synthetic data", xlabel="Elapsed time (s)", ylabel="Acceleration (m/s²)")
    axis.spines[["top", "right"]].set_visible(False)
    axis.grid(alpha=0.2)
    axis.legend(frameon=False)
    destination.mkdir(exist_ok=False)
    with (destination / "comparison_summary.csv").open("x", encoding="utf-8-sig", newline="") as file:
        writer = csv.writer(file)
        writer.writerow(["dataset_note", "condition", "sample_count", "min_acceleration", "max_acceleration", "unit"])
        for label, _, values in conditions:
            writer.writerow([NOTE, label, len(values), min(values), max(values), "m/s^2"])
    figure.savefig(destination / "synthetic_comparison.png", dpi=160)
    plt.close(figure)
    print(f"Explanatory synthetic data: {len(conditions)} conditions, {len(reference_times)} matching time samples each.")
    print("Created outputs/comparison_summary.csv and outputs/synthetic_comparison.png.")


if __name__ == "__main__":
    try:
        main()
    except (OSError, ValueError, csv.Error) as error:
        raise SystemExit(f"Stopped: {error}") from error