accessD {wavethresh} | R Documentation |
The coefficients from a wavelet expansion in a wavelet decomposition
structure (returned from wd
or wr
) are
packed into a single vector in that structure.
This function extracts the coefficients corresponding to a particular
resolution level.
accessD(wd.obj, level, boundary=FALSE)
wd.obj |
Wavelet decomposition structure from which you wish to extract the expansion coefficients. |
level |
The level that you wish to extract. If the "original" data has 2^m data points then there are m possible levels that you could want to access, indexed by 0,1,...{},(m-1). |
boundary |
If this argument is TRUE then all of the boundary correction values will be returned as well (note: the length of the returned vector may not be a power of 2). If boundary is false, then just the coefficients will be returned. If the decomposition (or reconstruction) was done using periodic boundary handling then this option has no effect. |
The wd (wr) function produces a wavelet decomposition (reconstruction) structure.
The need for this function is a consequence of the pyramidal structure
of Mallat's algorithm and the memory efficiency gain achieved by
storing the pyramid as a linear vector. AccessD obtains information about
where the coefficients appear from the fl.dbase component of
wd.obj, in particular the array fl.dbase$first.last.d
which
gives a complete specification of index numbers and offsets for
wd.obj$D
.
Note that this function and accessC only work on objects of class
wd
. Also, you have to use putD
to put wavelet
coefficients into a wd object.
A vector of the extracted coefficients.
wr
and wd
for background information;
accessC
, filter.select
,
threshold
, putC
, putD
.
example(wd) ## Get the 3rd level coefficients of a decomposition accessD(wds, level=3) ## Do a qqnorm plot to assess the normality of some coefficients qqnorm(accessD(wds, level=8))