fdPar | Language Reference for FDA Library
|
smooth.basis
A functional parameter object is a functional data object along with
additional slots specifying a roughness penalty, a smoothing parameter
and whether or not the functional parameter is to be estimated or held fixed.
Functional parameter objects are used as arguments to functions that
estimate functional parameters.
fdPar(fdobj=fd(), Lfdobj=int2Lfd(0), lambda=0, estimate=T, penmat=NULL)
T
, the functional parameter is
estimated, otherwise, it is held fixed.
(p> Functional parameters are often needed to specify initial
values for iteratively refined estimates, as is the case in
functions
register.fd
and
smooth.monotone
.
Often a list of functional parameters must be supplied to a
function as an argument, and it may be that some of these parameters
are considered known and must remain fixed during the analysis. This
is the case for functions
fRegress
and
pda.fd
,
for example.
# smooth the daily temperature data with a roughness # penalty # set up the fourier basis nbasis <- 365 dayrange <- c(0,365) daybasis <- create.fourier.basis(dayrange, nbasis) # Make temperature fd object # Temperature data are in 12 by 365 matrix tempav # See analyses of weather data. # Set up sampling points at mid days daytime <- (1:365)-0.5 # Convert the data to a functional data object tempfd <- smooth.basis(tempav, daytime, tempfdPar) # Set up the harmonic acceleration operator Lbasis <- create.constant.basis(dayrange); Lcoef <- matrix(c(0,(2*pi/365)^2,0),1,3) bfdobj <- fd(Lcoef,Lbasis) bwtlist <- fd2list(bfdobj) harmaccelLfd <- Lfd(3, bwtlist) # Define the functional parameter object for # smoothing the temperature data lambda <- 0.01 # minimum GCV estimate tempPar <- fdPar(daybasis365, harmaccelLfd, lambda) # smooth the data tempfd <- smooth.basis(daytime, tempav, tempPar)$fd # plot the temperature curves plot(tempfd)