机器学习之损失函数图像绘制

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本文链接： https://blog.csdn.net/qq_40605167/article/details/81275298

import numpy as np
import math
import matplotlib.pyplot as plt
plt.rcParams['font.sans-serif']=['SimHei']
plt.rcParams['axes.unicode_minus'] = False
plt.figure(figsize=(8, 5))
x = np.linspace(start=-2, stop=3,num =1001,dtype=np.float)
logi = np.log(1 + np.exp(-x))/math.log(2)
boost = np.exp(-x)
y_01 = x < 0
y_hinge = 1.0 - x
y_hinge[y_hinge < 0] = 0
plt.plot(x, logi, 'r-', mec='k', label='Logistic Loss', lw=2)
plt.plot(x, y_01, 'g-', mec='k', label='0/1 Loss', lw=2)
plt.plot(x, y_hinge, 'b-',mec='k', label='Hinge Loss', lw=2)
plt.plot(x, boost, 'm--',mec='k', label='Adaboost Loss',lw=2)
plt.grid(True, ls='--')
plt.legend(loc='upper right')
plt.title('损失函数')
plt.show()