1.定义函数

def get_counts(sequence):

    counts={}

    for x in sequence:

        if x  in counts:

            counts[x]+= 1

         else:

              counts[x]=1

    return counts

2.定义函数（利用python标准包）

from collections import defaultdict

def get_counts2(sequence):

    counts=defaultdict(int)#所以得值均会被初始化W为0

    for x in sequence:

        if x  in counts:

            counts[x]+= 1

    return counts

3.python标准库中找到collections.Counter类

from collections improt Counter

counter(sequence)