python简单实现感知机对偶形式

完全对照统计学习方法

from numpy import *
data_set=array([[[3,3],1],[[4,3],1],[[1,1],-1]])
eta=1
n=len(data_set)
gram=zeros((n,n))
a=[0,0,0]
b=0
def cal_gram(data_set):
    for i in range(len(data_set)):
        for j in range(len(data_set)):
            gram[i][j]=data_set[i][0][0]*data_set[j][0][0]+data_set[i][0][1]*data_set[j][0][1]
    return gram 
def f(x):
    ans=0
    for j in range(len(data_set)):
        ans+=a[j]*gram[x][j]*data_set[j][1]
    ans+=b
    return ans
def perception(data_set):
    global b
    flag=True
    for i in range(len(data_set)):
        if data_set[i][1]*f(i)<=0:
            flag=False
            a[i]+=eta
            b+=eta*data_set[i][1]
    if flag==False:
        perception(data_set)
cal_gram(data_set)
print(gram)
perception(data_set)
print(a,b)