statistic_functions.py 文件源码

def PSTDEV(df, n, price='Close', mu=None):
    """
    Population standard deviation of data
    """
    pstdev_list = []
    i = 0
    while i < len(df[price]):
        if i + 1 < n:
            pstdev = float('NaN')
        else:
            start = i + 1 - n
            end = i + 1
            pstdev = statistics.pstdev(df[price][start:end], mu)
        pstdev_list.append(pstdev)
        i += 1
    return pstdev_list