[scikit-learn] PolynomialFeatures

[Sole Galli]

Hi Michael, Nicolas,

Thank you both, that is very helpful!

Best wishes

Sole

On Sun, 24 Nov 2019 at 03:37, Michael Eickenberg <
michael.eickenberg at gmail.com> wrote:

> I think it might generate a basis that is capable of generating what you
> describe above, but feature expansion concretely reads as
>
> 1, a, b, c, a ** 2, ab, ac, b ** 2, bc, c ** 2, a ** 3, a ** 2 * b, a ** 2
> * c, a* b ** 2, abc, a*c**2, b**3, b**2 * c, b*c**2, c**3
>
> Hope this helps
>
> On Fri, Nov 22, 2019 at 8:50 AM Sole Galli <solegalli1 at gmail.com> wrote:
>
>> Hello team,
>>
>> Can I double check with you that I understand correctly what the
>> PolynomialFeatures() is doing under the hood?
>>
>> If I set it like this:
>>
>> poly = PolynomialFeatures(degree=3, interaction_only=False,
>> include_bias=False)
>>
>> and I fit it on a dataset with 3 variables, a,b and c.
>>
>> Am I correct to say that the fit() method creates all possible
>> combinations like this:
>> a;
>> b;
>> c;
>> (a+b)^2
>> (a+b)^3
>> (a+c)^2
>> (a+c)^3
>> (c+b)^2
>> (c+b)^3
>> (a+b+c)^2
>> (a+b+c)^3
>>
>> And the transform() generates the expansion, without the constant that
>> multiplies the interactions and avoiding duplicated terms after the
>> expansion?
>>
>> Thanks for the help.
>>
>> Kind regards
>>
>> Sole
>>
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