R/comp_kernel_ideas.R

In goldingn/gpe: Gaussian Process Everything

# # play at packing and unpacking compositional kernels
# rm(list = ls())
# # library(gpe)
# 
# k1 <- rbf('a')
# k2 <- lin(c('a', 'b'))
# k3 <- k1 + k1 * k2
# k3
# 
# getObject <- gpe:::getObject
# unpackKernel <- gpe:::unpackKernel
# repackKernel <- gpe:::repackKernel
# 
# # build getParVec and setParVec into getParameters and setParameters
# # so that users can upadte parameters of fitted kernels
# # then just use unlist/relist magic for the model fitting bit
# # need to let users pass a list to setParameters too 
# # (via dots, just check for list case)
# 
# 
# # functions to test and switch between transformed and untransformed
# # versions of parameters, in a parameter vector list
# 
# # then we're nearly ready for gradient-free optimisation!
# 
# # function to identify the specific kernel parameter(s) of interest
# 
# 
# 
# 
# # option 1:
# # make a setObject function (convert object list into a function)
# # write a repackKernel function by parsing the symbolic string
# 
# # option 2:
# # use relist functions; write a function to listify a compositional
# # kernel, then unlist, modify, and relist it
# 
# A <- exp
# B <- log
# C <- pmin
# BC <- list(B = B, C = C)
# ABC <- list(A = A, BC = BC)
# 
# flesh <- unlist(ABC)
# ABC2 <- relist(flesh, ABC)
# 
# # convert a compositional kernel object into a list via recursion
# as.list.kernel <- function (kernel, recursive = TRUE) {
#   checkKernel(kernel)
#   object <- getObject(kernel)
#   
#   # for now, throw an error the kernel is compositional
#   if (object$type %in% c('sum', 'prod', 'kron')) {
#     object[2:3] <- lapply(object[2:3], as.list.kernel)
#   } else {
#     class(object) <- 'kernel_object'
#   }
#   
#   return (object)
#   
# }
# 
# # think this won't work as the type is an element in the list
# # it may need to be an attribute instead.
# # shouldn't be a problem for the basis kernels, though that
# # might also screw up unlist/relist
# kernel_list <- as.list.kernel(k3)
# kernel_list_flat <- unlist(kernel_list, recursive = FALSE)
# 
# 
# str(kernel_list_flat, 2)
# 
# args(getObject)
# 
# as.kernel.list <- function (list) {
#   
# }
# 
#