计算频率

a = [1,2,3,4,5,6,7,8,6,5,4,3,2]
d= {}
for n in a:
    d[n] = d.get(n,0)+1
ls = list(d.items())
print(d)   #{1: 1, 2: 2, 3: 2, 4: 2, 5: 2, 6: 2, 7: 1, 8: 1}
print(ls)  #[(1, 1), (2, 2), (3, 2), (4, 2), (5, 2), (6, 2), (7, 1), (8, 1)]
ls.sort(key=lambda x:x[1],reverse=True)
a,b = ls[0]
print(‘{}:{}‘.format(‘a,b‘))   #