swthresh {SpherWave} | R Documentation |
This function performs various ways to threshold a `swd' class object.
swthresh(swd, policy, by.level, type, nthresh, value = 0.1, Q = 0.05)
swd |
an object of class `swd' |
policy |
threshold technique. At present the possible policies are `"universal"', `"probability"', `"fdr"', `"Lorentz"' and `"sure"'. |
by.level |
If FALSE, then perform a global threshold. If TRUE, a thresholding value is computed and applied separately to each resolution level. |
type |
the type of thresholding. This can be `"hard"', `"soft"' or `"Lorentz"'. |
nthresh |
the number of resolution levels to be thresholded in the decomposition |
value |
the user supplied threshold represented by quantile level for `"probability"' policy |
Q |
parameter for the false discovery rate of `"fdr"' policy |
This function thresholds or shrinks details stored in a `swd' object and returns the thresholded details in a modified `swd' object. For level-dependent thresholding, `"universal"', `"Lorentz"' and `"fdr"' are provided. Only hard type thresholding is proper for `"probability"' thresholding. Also note that only soft type thresholding is proper for `"sure"' thresholding.
An object of class `swd'. This object is a list with the following components.
obs |
observations |
latlon |
grid points of observation sites in degree |
netlab |
vector of labels representing sub-networks |
eta |
bandwidth parameters for Poisson kernel |
method |
extrapolation methods, `"ls"' or `"pls"' |
approx |
if TRUE, approximation is used. |
grid.size |
grid size (latitude, longitude) of extrapolation site |
lambda |
smoothing parameter for penalized least squares method |
p0 |
starting level for extrapolation. Resolution levels p0+1, ..., L is used for extrapolation. |
gridlon |
longitudes of extrapolation sites in degree |
gridlat |
latitudes of extrapolation sites in degree |
nlevels |
the number of multi-resolution levels |
coeff |
interpolation coefficients |
field |
extrapolation on grid.size |
density1 |
density of SBF |
latlim |
range of latitudes in degree |
lonlim |
range of longitudes in degree |
global |
List of successively smoothed data |
density |
density of SW coefficients |
detail |
List of details at different resolution levels |
swcoeff |
spherical wavelet coefficients |
thresh.info |
thresholding information and ranges of local components before thresholding |
Oh, H-S. and Li, T-H. (2004) Estimation of global temperature fields from scattered observations by a spherical-wavelet-based spatially adaptive method. Journal of the Royal Statistical Society Ser. B, 66, 221–238.
### Observations of year 1967 #data(temperature) #names(temperature) # Temperatures on 939 weather stations of year 1967 #temp67 <- temperature$obs[temperature$year == 1967] # Locations of 939 weather stations #latlon <- temperature$latlon[temperature$year == 1967, ] ### Network design by BUD #data(netlab) ### Bandwidth for Poisson kernel #eta <- c(0.961, 0.923, 0.852, 0.723, 0.506) ### SBF representation of the observations by pls #out.pls <- sbf(obs=temp67, latlon=latlon, netlab=netlab, eta=eta, # method="pls", grid.size=c(50, 100), lambda=0.89) ### Decomposition #out.dpls <- swd(out.pls) ### Thresholding #out.univ <- swthresh(out.dpls, policy="universal", by.level=TRUE, # type="hard", nthresh=4)