Add steps for basis functions

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Pipeable steps for feature engineering and data preprocessing to prepare for modeling

https://recipes.tidymodels.org

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Add steps for basis functions #22

Open topepo opened 7 years ago

topepo commented 7 years ago

[x] natural splines
[ ] restricted cubic splines
[x] orthogonal polynomials
[x] periodic splines

hadley commented 7 years ago

A periodic spline?

topepo commented 7 years ago

Sure! I'd never seen those and had to look it up.

hadley commented 7 years ago

I've never actually used them in base R because they have a different interface to all the other spline functions, but they seem useful.

alexpghayes commented 5 years ago

mgcv provides utilities that do a ton of cool basis function calculations that would be cool to incorporate in somewhere.

alexpghayes commented 5 years ago

@max Some examples that use periodic splines (although I think the phrase "cyclic splines" is better for Googling). Lots of people use s(x, bs = "cc") in mgcv:

tspeidel commented 4 years ago

A bit late too the discussion. @topepo any plan to add restricted cubic splines? e.g. tidymodels::step_rcs() They are used a lot and advocated by the likes of Harrell, Steyerberg et al.