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section 1.4.3 of the book "Machine Learning - A Probabilistic Perspective" gives an example about KNN:

the input is two dimensional, we have three classes, and K = 10

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which contains a computation

$e_{10}{(0.1)} = 0.8$

what does that mean? what is the name of this computation?

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    $\begingroup$ $0.1^{1/10} = 0.79432823472428150206591828283639$, because $e_{D}(f) = f^{1/D}$ $\endgroup$
    – user158565
    Commented Jul 27, 2019 at 22:44
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    $\begingroup$ @user158565 thanks man! plz mv your comments to answer, I'll accept it $\endgroup$
    – czlsws
    Commented Jul 27, 2019 at 22:54
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    $\begingroup$ Too short. Cannot be Answer. $\endgroup$
    – user158565
    Commented Jul 27, 2019 at 22:56

1 Answer 1

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This section uses this formula to compute

the expected edge length of this cube

$e_{D}(f) = f^{1/D}$

where, D = 10, so the original formula is $f^{1/10}$

and we want to base our estimate on 10%

which means f = 10% = 0.1

put above together

$e_{D}(f) = f^{1/D} = 0.1^{1/10} = 0.79 \approx 0.8$

using "= 0.8" other than "$\approx 0.8$" in OP may confused you.

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