概率论python代码

 1 1.指数分布
 2 import matplotlib
 3 import matplotlib.pyplot as plt
 4 import numpy as np
 5 matplotlib.use('Agg')
 6 x = np.linspace(0, 2)
 7 
 8 
 9 def func(lmd,x):
10     return lmd*np.exp(-lmd*x)
11 
12 
13 lambd1 = 1
14 lambd2 = 2
15 
16 fig,ax=plt.subplots(figsize=(6,5))
17 plt.rcParams['font.sans-serif']=['SimSun']
18 
19 plt.title("指数分布",fontsize=20)
20 y1=func(lambd1,x)
21 y2=func(lambd2,x)
22 plt.plot(x,y1,label='lambda=1',linewidth=2,linestyle=':')
23 plt.plot(x,y2,label='lambda=2',linewidth=3)
24 plt.figtext(0.05,0.9,'$y$')
25 plt.figtext(0.97,0.05,'$x$')
26 plt.legend(['λ=1','λ=2'])
27 
28 plt.savefig('new1.png')
29 
30 
31 2.均匀分布F(x)
32 import matplotlib
33 import matplotlib.pyplot as plt
34 import numpy as np
35 matplotlib.use('Agg')
36 x = np.linspace(0, 4,1000)
37 a = 1
38 b = 3
39 
40 interval0 = [0 if (i <= a) else 0 for i in x]
41 interval1 = [1 if (a < i < b) else 0 for i in x]
42 interval2 = [1 if (i >= b) else 0 for i in x]
43 
44 y = interval0 + (x - a)*interval1 / (b - a)+  interval2
45 
46 fig, ax = plt.subplots()
47 ax.set_yticks([0, 1])
48 ax.set_xticks([a,b])
49 ax.set_xticklabels(['$a$','$b$'])
50 plt.figtext(0.05,0.9,'$F(x)$')
51 plt.figtext(0.9,0.05,'$x$')
52 
53 plt.plot(x, y, label='1')
54 plt.show()
55 plt.savefig('new2.png')
56 均匀分布f(x)
57 import matplotlib
58 import matplotlib.pyplot as plt
59 import numpy as np
60 matplotlib.use('Agg')
61 x = np.linspace(0, 4, 1000)
62 a = 1
63 b = 3
64 y = [1 / (b - a) if (a < i < b) else 0 for i in x]
65 
66 fig, ax = plt.subplots()
67 ax.set_yticks([0, 1])
68 ax.set_xticks([a, b])
69 ax.set_xticklabels(['$a$', '$b$'])
70 plt.figtext(0.05, 0.9, '$f(x)$')
71 plt.figtext(0.9, 0.05, '$x$')
72 
73 plt.plot(x, y, label='1')
74 plt.savefig('new3.png')