detreeexp2_4.m

支持向量机工具箱

%设置全局变量
global WM Model_Year bad numobs
global  x y j  tree


%Treefit函数能为数据集找到适合的决策树。

tree = treefit(WM(:,1:2), Model_Year);

% treeval计算决策树的代价
[dtnum,dtnode,dtclass] = treeval(tree, WM(:,1:2));

%计算决策树分类误差
bad_d = ~strcmp(dtclass,Model_Year);
sum(bad_d) / numobs;

%创建含有x轴，y轴的栅格图来显示决策树分类区域
[grpnum,node,grpname] = treeval(tree, [x y]);
gscatter(x,y,grpname,'crk','odv')
xlabel('车重(吨)');
ylabel('里/加仑');
hold on;
plot(WM(bad_d,1), WM(bad_d,2), 'kx');
hold off;