INT104-lab4

python 统计频率

 

 

 1 import csv
 2 import numpy as np
 3 
 4 
 5 # the method for parse data into a matrix
 6 def input_data_to_matrix():
 7     csv_file = open('binary_data.csv')
 8     csv_reader = csv.reader(csv_file, delimiter=',')
 9     Matrix = []
10     N = 0
11     for row in csv_reader:
12         Matrix.append([int(i) for i in row])
13         N += 1
14     print("\nShowing the matrix:\n")
15     print(np.array(Matrix))
16     return Matrix, N
17 
18 
19 # the method to compute p(ai=?|l=?)
20 def p(i: int, ai: int, l: int, Matrix: list):
21     n = N = 0
22     for a in Matrix:
23         if a[5] == l:
24             if a[i] == ai:
25                 n += 1
26             N += 1
27     print("p(a[{}]={}|l={})={}".format(i, ai, l, n / N))
28 
29 
30 if __name__ == '__main__':
31     # part 1
32     # Reading data and parse its content into a matrix
33     # (20 scores)
34     Matrix, N = input_data_to_matrix()
35 
36     # part 2
37     # Compute the prior probabilities p(l = 0) and p(l = 1)
38     # (20 scores)
39     print("\nResult of p(l=0) and p(l=1)\n")
40     n = [0, 0]
41     for a in Matrix:
42         if a[5] == 0:
43             n[0] += 1
44         else:
45             n[1] += 1
46     for i in range(2):
47         print("p(l={})={}".format(i, n[i] / N))
48 
49     # part 3
50     # Compute the conditional probabilities
51     # p(ai=0|l=0),i=0,1,2,3,4 and p(ai=1|l=0),i=0,1,2,3,4,
52     # p(ai=0|l=1),i=0,1,2,3,4 and p(ai=1|l=1),i=0,1,2,3,4
53     # (60 scores)
54     No = 1
55     for l in range(2):
56         for ai in range(2):
57             print("\nResult Group_{} of: p(ai={}|l={}),i=0,1,2,3,4\n".format(No, ai, l))
58             No += 1
59             for i in range(5):
60                 p(i, ai, l, Matrix)

 

posted @ 2021-03-22 17:26  墨鳌  阅读(52)  评论(0)  编辑  收藏  举报