Generate the expected kernel library based on user-specified dataframe.
define_library(kern_par = NULL)(dataframe, K*3) A dataframe indicating the parameters of base kernels to fit kernel effect. See Details.
(list of length K) A list of kernel functions given by user. Will be overwritten to linear kernel if kern_par is NULL.
It creates a kernel library according to the parameters given in kern_par.
* kern_par: for a library of K kernels, the dimension of this dataframe is K*3. Each row represents a kernel. The first column is method, with entries of character class. The second and the third are l and p respectively, both with entries of numeric class.
method: generate_kernel