서로의 코드를
올리고, 써보고, 평가합니다

def valid_range(values: np.ndarray, threshold: float) -> tuple[int, int] | None:
    idx = np.where(values > threshold)[0]
    if idx.size == 0:
        return None
    return int(idx[0]), int(idx[-1])
def aligned_difference(meas: pd.Series, ref: pd.Series, threshold: float) -> np.ndarray:

def parse_row_count(text: str, fallback: int) -> int:
    try:
        n = int(str(text).strip())
    except ValueError:
        return fallback
    return n if n > 0 else fallback

def pixel_columns(df: pd.DataFrame, prefix: str) -> list[str]:
    cols = [c for c in df.columns if str(c).startswith(prefix) and str(c)[len(prefix):].isdigit()]
    return sorted(cols, key=lambda c: int(str(c)[len(prefix):]))
def sum_pixels_by_row(df: pd.DataFrame, prefix: str) -> pd.DataFrame:
    dff = df.copy()
    cols = pixel_columns(dff, prefix)

def apply_plot_style() -> None:
    try:
        plt.style.use('seaborn-v0_8-whitegrid')
    except OSError:
        plt.style.use('seaborn-whitegrid')
    plt.rcParams['font.family'] = 'Malgun Gothic'

def preprocess(y: pd.Series, detrend: str, window: str) -> tuple[np.ndarray, float]:
    arr = pd.to_numeric(y, errors='coerce').dropna().to_numpy(dtype=float)
    if arr.size < 2:
        return arr, 1.0
    if detrend == '선형추세 제거':
        x = np.arange(arr.size, dtype=float)

def dominant_period(series: pd.Series) -> float | None:
    s = pd.to_numeric(series, errors='coerce').dropna()
    if len(s) < 4:
        return None
    normalized = (s - s.mean()) / (s.std() + 1e-10)
    power = np.abs(np.fft.rfft(normalized.to_numpy())) ** 2