[clircle]

I think most or all of these models are in the R Standard lib

[wdkrnls]

Not all as far as I know. For ridge regression you will want to install glmnet, for example. mgcv which is usually shipped with R provides access to a few common fast kernels which seem to be the ones python programmers are familiar with.

[clircle]

Can use lm.ridge from MASS instead of glmnet, but yeah there’s going to be some smoother not in R standard library

[wdkrnls]

mgcv also provides many more varieties of splines than base R.