I understand that there is a function in R called
poly() that can generate orthogonal polynomials--useful for applying on input variables before running a predictive model.
My question is that what is the role of categorical variables when we generate polynomials? Are they to be excluded?
Dan, Thank you for your kind response. I'm not sure I understand it completely - let me explain the query in more detail. I'm trying to run logistic regression using glmnet on Titanic dataset.
Let us assume shortened set of columns:
- * class(factor with three levels 1, 2 ,3),
* sex(factor: male, female),
* Age (integer),
*survived(factor & target variable 0 or 1).
I've seen examples with numeric input variables, where one can pass the entire input set to the poly() function and get polynomial features as output.
Your response is highly appreciated.