Machine Learning 第七波编程作业——K-means Clustering and Principal Component Analysis

仅列出核心代码：

1.findClosestCentroids.m

m = size(X, 1);
len = zeros(K, 1);
for i = 1:m
    for j = 1:K
        len(j) = norm(X(i, :) - centroids(j, :))^2;
    end
    [~, idx(i)] = min(len);
end

2.computeCentroids.m

for k = 1:K
    ind = find(idx == k);
    centroids(k, :) = mean(X(ind, :));
end

3.pca.m

Sigma = X'*X/m;
[U,S,~] = svd(Sigma);

4.projectData.m

Z = X * U(:, 1:K);

5.recoverData.m

X_rec = Z * U(:, 1:K)';

课程地址：https://www.coursera.org/course/ml