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@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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