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把高维空间中松散分布的样本,通过线性或非线性变换压缩到一个低维的子空间中,在低维的子空间中使样本的分布更紧凑、更有利于分类,同时使计算复杂度减少。
PCA的思想为:
这一题想了很久,没有得到答案,这里记录一下想法
对于样本构成的矩阵 X 为 D×N 的矩阵,投影矩阵 W 为 D×D' 的矩阵,投影后的样本 X' = WTX 为 D'×N 的矩阵。
X
D×N
W
D×D'
X' = WTX
D'×N
当 D' > N 时,存在行向量可被其他行向量线性表出。
D' > N
当 D' = N 时,感觉是可以的。。。。。
D' = N
The text was updated successfully, but these errors were encountered:
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习题9-2 证明对于 𝑁 个样本(样本维数𝐷 > 𝑁) 组成的数据集, 主成分分析的有效投影子空间不超过𝑁 − 1维
解答
子空间分析
把高维空间中松散分布的样本,通过线性或非线性变换压缩到一个低维的子空间中,在低维的子空间中使样本的分布更紧凑、更有利于分类,同时使计算复杂度减少。
PCA的思想为:
有效投影子空间
这一题想了很久,没有得到答案,这里记录一下想法
对于样本构成的矩阵
X
为D×N
的矩阵,投影矩阵W
为D×D'
的矩阵,投影后的样本X' = WTX
为D'×N
的矩阵。当
D' > N
时,存在行向量可被其他行向量线性表出。当
D' = N
时,感觉是可以的。。。。。The text was updated successfully, but these errors were encountered: