我正在阅读Ethem Alpaydin的“机器学习入门”,我遇到了最近的质心分类器并试图实现它。我想我已经正确实施了分类器,但我的准确率只有68%。那么,最近的质心分类器本身效率低下,还是在我的实现中出现了一些错误(如下所示)?最近的质心分类器真的效率低下吗?
该数据集包含含有4个功能和有2个输出类1372个数据点 我的MATLAB实现:
DATA = load("-ascii", "data.txt");
#DATA is 1372x5 matrix with 762 data points of class 0 and 610 data points of class 1
#there are 4 features of each data point
X = DATA(:,1:4); #matrix to store all features
X0 = DATA(1:762,1:4); #matrix to store the features of class 0
X1 = DATA(763:1372,1:4); #matrix to store the features of class 1
X0 = X0(1:610,:); #to make sure both datasets have same size for prior probability to be equal
Y = DATA(:,5); # to store outputs
mean0 = sum(X0)/610; #mean of features of class 0
mean1 = sum(X1)/610; #mean of featurs of class 1
count = 0;
for i = 1:1372
pre = 0;
cost1 = X(i,:)*(mean0'); #calculates the dot product of dataset with mean of features of both classes
cost2 = X(i,:)*(mean1');
if (cost1<cost2)
pre = 1;
end
if pre == Y(i)
count = count+1; #counts the number of correctly predicted values
end
end
disp("accuracy"); #calculates the accuracy
disp((count/1372)*100);