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MATLAB实现朴素贝叶斯分类

news 来源：原创 2025/5/1 17:24:28

朴素贝叶斯（Naive Bayes）是一种基于贝叶斯定理的分类算法，它假设特征之间相互独立，从而简化了计算复杂性。该算法常用于文本分类、垃圾邮件过滤、情感分析等应用场景。

MATLAB实现鸢尾花数据集分类代码如下：

clear
load fisheriris
X = meas(:,1:2);
Y = species;
labels = unique(Y);

figure;
gscatter(X(:,1), X(:,2), species,'rgb','osd');
xlabel('Sepal length');
ylabel('Sepal width');
mdl = fitcnb(X,Y);
[xx1, xx2] = meshgrid(4:.01:8,2:.01:4.5);
XGrid = [xx1(:) xx2(:)];
[predictedspecies,Posterior,~] = predict(mdl,XGrid);

sz = size(xx1);
s = max(Posterior,[],2);
figure
hold on
surf(xx1,xx2,reshape(Posterior(:,1),sz),'EdgeColor','none')
surf(xx1,xx2,reshape(Posterior(:,2),sz),'EdgeColor','none')
surf(xx1,xx2,reshape(Posterior(:,3),sz),'EdgeColor','none')
xlabel('Sepal length');
ylabel('Sepal width');
colorbar
view(2)
hold off

figure('Units','Normalized','Position',[0.25,0.55,0.4,0.35]);
hold on
surf(xx1,xx2,reshape(Posterior(:,1),sz),'FaceColor','red','EdgeColor','none')
surf(xx1,xx2,reshape(Posterior(:,2),sz),'FaceColor','blue','EdgeColor','none')
surf(xx1,xx2,reshape(Posterior(:,3),sz),'FaceColor','green','EdgeColor','none')
xlabel('Sepal length');
ylabel('Sepal width');
zlabel('Probability');
legend(labels)
title('Classification Probability')
alpha(0.2)
view(3)
hold off

运行结果如下：