def ROC(df, n, price='Close'):
    """
    Rate of change : ((price/prevPrice)-1)*100
    Returns: list of floats = jhta.ROC(df, n, price='Close')
    """
    roc_list = []
    for i in range(len(df[price])):
        if i + 1 < n:
            roc = float('NaN')
        else:
            roc = (df[price][i] / df[price][i - n] - 1) * 100
        roc_list.append(roc)
    return roc_list
