%設(shè)置全局變量 meas species bad numobs
global meas species bad numobs quadclass

%散點(diǎn)圖
gscatter(meas(:,1), meas(:,2), species,'mgb','vsp');
xlabel('Sepal 長(zhǎng)度');
ylabel('Sepal 寬度');

%二次分類
quadclass= classify(meas(:,1:2),meas(:,1:2),species);

%計(jì)算錯(cuò)誤分類      strcmp函數(shù)比較字符串
bad = ~strcmp(quadclass,species);
%計(jì)算meas第一列大小
numobs = size(meas,1);
%sum函數(shù)求元素的和
sum(bad) / numobs;

%在散點(diǎn)圖上顯示錯(cuò)誤分類 用x表示
hold on;
plot(meas(bad,1), meas(bad,2), 'kx');
hold off;