使用python實現畫AR模型時序圖
阿新 • • 發佈:2020-01-09
背景:
用python畫AR模型的時序圖。
結果:
程式碼:
import numpy as np import matplotlib.pyplot as plt """ AR(1)的時序圖:x[t]=a*x[t-1]+e """ num = 2000 e = np.random.rand(num) x = np.empty(num) """ 平穩AR(1) """ a = -0.5 x[0] = 2 for i in range(1,num): x[i] = a*x[i-1]+e[i] plt.subplot(321,title = "AR({0}):x[t]={1}*x[t-1]+e".format(1,a)) plt.plot(x,"or") """ 非平穩AR(1) """ a = -1.01 x[0] = 2 for i in range(1,num): x[i] = a*x[i-1]+e[i] plt.subplot(322,".b") """ 平穩AR(2) """ a = -0.2 b = 0.7 x[0] = 2 for i in range(2,num): x[i] = a*x[i-1]+b*x[i-2]+e[i] plt.subplot(323,title = "AR({0}):x[t]={1}*x[t-1]+{2}*x[t-2]+e".format(2,a,b)) plt.plot(x,"og") """ 非平穩AR(2) """ a = -0.3 b = 0.8 x[0] = 2 for i in range(2,num): x[i] = a*x[i-1]+b*x[i-2]+e[i] plt.subplot(324,".y") """ 非平穩AR(2) """ a = -0.2 b = 0.8 x[0] = 2 for i in range(2,num): x[i] = a*x[i-1]+b*x[i-2]+e[i] plt.subplot(313,"+",color="purple") plt.show()
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