vaws {aws} | R Documentation |
vector valued version of function aws
The function implements the propagation separation approach to
nonparametric smoothing (formerly introduced as Adaptive weights smoothing)
for varying coefficient likelihood models with vector valued response on a 1D, 2D or 3D grid.
Description
The function implements a version the propagation separation approach that uses vector valued instead of scalar responses.
Usage
vaws(y, kstar = 16, sigma2 = 1, mask = NULL, scorr = 0, spmin = 0.25,
ladjust = 1, wghts = NULL, u = NULL, maxni = FALSE)
vawscov(y, kstar = 16, invcov = NULL, mask = NULL, scorr = 0, spmin = 0.25,
ladjust = 1, wghts = NULL, u = NULL, maxni = FALSE)
Arguments
y |
|
kstar |
maximal number of steps to employ. Determines maximal bandwidth. |
sigma2 |
specifies a homogeneous error variance. |
invcov |
array of voxelwise inverse covariance matrixes, first index corresponds to upper diagonal inverse covariance matrix. |
mask |
logical mask. All computations are restrikted to design poins within the mask. |
scorr |
The vector |
spmin |
determines the form (size of the plateau) in the adaptation kernel. Not to be changed by the user. |
ladjust |
factor to increase the default value of lambda |
wghts |
|
u |
a "true" value of the regression function, may be provided to
report risks at each iteration. This can be used to test the propagation condition with |
maxni |
If TRUE use |
Details
see aws
. Expets vector valued responses. Currently only implements the case of additive Gaussian errors.
Value
returns anobject of class aws
with slots
y = "numeric" |
y |
dy = "numeric" |
dim(y) |
x = "numeric" |
numeric(0) |
ni = "integer" |
integer(0) |
mask = "logical" |
logical(0) |
theta = "numeric" |
Estimates of regression function, |
hseq = "numeric" |
sequence of bandwidths employed |
mae = "numeric" |
Mean absolute error for each iteration step if u was specified, numeric(0) else |
psnr = "numeric" |
Peak signal-to-noise ratio for each iteration step if u was specified, numeric(0) else |
var = "numeric" |
approx. variance of the estimates of the regression function. Please note that this does not reflect variability due to randomness of weights. |
xmin = "numeric" |
numeric(0) |
xmax = "numeric" |
numeric(0) |
wghts = "numeric" |
numeric(0), ratio of distances |
degree = "integer" |
0 |
hmax = "numeric" |
effective hmax |
sigma2 = "numeric" |
provided or estimated (inverse) error variance |
scorr = "numeric" |
scorr |
family = "character" |
family |
shape = "numeric" |
shape |
lkern = "integer" |
integer code for lkern, 1="Plateau", 2="Triangle", 3="Quadratic", 4="Cubic", 5="Gaussian" |
lambda = "numeric" |
effective value of lambda |
ladjust = "numeric" |
effective value of ladjust |
aws = "logical" |
aws |
memory = "logical" |
memory |
homogen = "logical" |
homogen |
earlystop = "logical" |
FALSE |
varmodel = "character" |
"Constant" |
vcoef = "numeric" |
numeric(0) |
call = "function" |
the arguments of the call to |
Note
use setCores='number of threads'
to enable parallel execution.
Author(s)
Joerg Polzehl, polzehl@wias-berlin.de, https://www.wias-berlin.de/people/polzehl/
References
J. Polzehl, K. Tabelow (2019). Magnetic Resonance Brain Imaging: Modeling and Data Analysis Using R. Springer, Use R! series. Appendix A. Doi:10.1007/978-3-030-29184-6.
J. Polzehl, V. Spokoiny, Adaptive Weights Smoothing with applications to image restoration, J. R. Stat. Soc. Ser. B Stat. Methodol. 62 , (2000) , pp. 335–354. DOI:10.1111/1467-9868.00235.
J. Polzehl, V. Spokoiny, Propagation-separation approach for local likelihood estimation, Probab. Theory Related Fields 135 (3), (2006) , pp. 335–362. DOI:10.1007/s00440-005-0464-1.
See Also
See also aws
, vpaws
,link{awsdata}
Examples
## Not run:
setCores(2)
y <- array(rnorm(4*64^3),c(4,64,64,64))
yhat <- vaws(y,kstar=20)
## End(Not run)