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A comment on Principal Component Projection Without Principal Component Analysis. Parent comment

Re:Principal Component Projection Without Principal Componen... by eggie5 on Wednesday February 24, 2016 @02:45AM (#11165196)
I think the paper disagrees w/ you: "Computing principal components can be an expensive task..."
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Re:Principal Component Projection Without Principal Componen... by hiddencost on Wednesday February 24, 2016 @04:26AM (#11165534)
The result of PCA is a linear projection matrix. Applying that projection is fast.

You learn the projection from an initial dataset. That is "slow". You apply the projection to new data. That is "fast".

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Re:Principal Component Projection Without Principal Componen... by eggie5 on Wednesday February 24, 2016 @11:47AM (#11168100)
thanks for explaining
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Re:Principal Component Projection Without Principal Componen... by JupiterMoon on Wednesday February 24, 2016 @04:23AM (#11165522)
I think you misunderstood the OP. Once you have the PCs (and loadings) for a dataset converting new data into the same axis system is just a linear conversion.
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