백분위수·Z점수 계산기

def percentile_rank(data: list[float], value: float) -> float:
    """Calculate the percentile rank of a value in a dataset."""
    n = len(data)
    if n == 0:
        return 0.0
    count_below = sum(1 for x in data if x < value)
    return (count_below / n) * 100

def percentile_value(data: list[float], p: float) -> float:
    """Find the value at the p-th percentile (0-100)."""
    if not data:
        return 0.0
    sorted_data = sorted(data)
    index = (p / 100) * (len(sorted_data) - 1)
    lower = int(index)
    upper = lower + 1
    if upper >= len(sorted_data):
        return sorted_data[-1]
    return sorted_data[lower] + (index - lower) * (sorted_data[upper] - sorted_data[lower])

data = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
print(percentile_rank(data, 75))   # 70.0
print(percentile_value(data, 25))  # 32.5