<25>python学习笔记——统计序列中元素的出现频度

方法一：用字典方法统计序列中元素的出现频度

ange(30)] ##创建一个随机数序列
data
Out[57]:
[5,
13,
0,
1,
17,
8,
7,
3,
19,
15,
19,
15,
11,
17,
16,
12,
9,
17,
4,
0,
17,
4,
1,
14,
2,
2,
6,
12,
3,
2]
c = dict.fromkeys(data,0) ##创建一个字典，用随机数序列做键，默认初始值为0
c
Out[59]:
{0: 0,
1: 0,
2: 0,
3: 0,
4: 0,
5: 0,
6: 0,
7: 0,
8: 0,
9: 0,
11: 0,
12: 0,
13: 0,
14: 0,
15: 0,
16: 0,
17: 0,
19: 0}
for x in data: ##遍历建，如果键相同，就加1.就可以得出序列中元素出现的次数
c[x] +=1

c
Out[61]:
{0: 2,
1: 2,
2: 3,
3: 2,
4: 2,
5: 1,
6: 1,
7: 1,
8: 1,
9: 1,
11: 1,
12: 2,
13: 1,
14: 1,
15: 2,
16: 1,
17: 4,
19: 2}
方法二：使用collection.Counter对象

Counter

是一个简单的计数器，例如，统计字符出现的个数：

代码接方法一

from collections import Counter
c2 = Counter(data)
c2
Out[64]:
Counter({0: 2,
1: 2,
2: 3,
3: 2,
4: 2,
5: 1,
6: 1,
7: 1,
8: 1,
9: 1,
11: 1,
12: 2,
13: 1,
14: 1,
15: 2,
16: 1,
17: 4,
19: 2})
c2.most_common(3)##most_common 方法筛选频率最高的3个
Out[65]:
[(17, 4), (2, 3), (0, 2)]