python 求众数 含重复的众数

def mode(arr):
    dict_cnt = {}
    for x in arr:
        dict_cnt[x] = dict_cnt.get(x,0)+1
    max_cnt = max(dict_cnt.values())
    most_values = [k for k,v in dict_cnt.items() if v==max_cnt]
    s = 0.0
    for x in most_values:
        s = s + x
    return s/len(most_values)

arr = [2,2,3,3]
mode(arr)
#2.5