众数定义及示例

def Mode(t):
    """众数"""
    if not t:
        return None
    arr = __getfreq(t)
    if arr[0][0] == 1:
        return None
    else:
        for k, g in itertools.groupby(arr, key=lambda x: x[0]):
            return [t[1] for t in g]


def __getfreq(t):
    """获取t中每个值及其出现次数"""
    arr = sorted(t)
    alist = []
    for k, g in itertools.groupby(arr):
        alist.append((len(list(g)), k))
    alist.sort(key=lambda x: x[0], reverse=True)
    return alist