wavethresh: accessD.mwd – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

accessD.mwd

Get wavelet coefficients from multiple wavelet structure (mwd).

Description

The wavelet coefficients from a multiple wavelet decomposition structure, mwd.object, (e.g. returned from mwd) are packed into a single matrix in that structure. This function extracts the coefficients corresponding to a particular resolution level.

Usage

## S3 method for class 'mwd'
accessD(mwd, level, ...)

Arguments

`mwd`	Multiple 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 `mwd$filter$npsi*2^m` data points (`mwd$filter$npsi` being the multiplicity of the multiple wavelets) then there are m possible levels that you could want to access, indexed by 0,1,...,(m-1)
`...`	any other arguments

Details

The mwd function produces a multiple wavelet decomposition object .

The need for this function is a consequence of the pyramidal structure of Mallats algorithm and the memory efficiency gain achieved by storing the pyramid as a linear matrix. AccessD obtains information about where the coefficients appear from the fl.dbase component of mwd, in particular the array fl.dbase$first.last.d which gives a complete specification of index numbers and offsets for mwd$D.

Note that this function and accessC only work on objects of class mwd to extract coefficients. You have to use putD.mwd to insert wavelet coefficients into a mwd object.

See Downie and Silverman, 1998.

Value

A matrix with mwd$filter$npsi rows containing the extracted coefficients.

RELEASE

Tim Downie 1995-6

Author(s)

G P Nason

Examples

#
# Get the 3rd level of smoothed data from a decomposition
#
data(ipd)
accessD.mwd(mwd(ipd), level=3)

wavethresh

Wavelets Statistics and Transforms

v4.6.8

GPL (>= 2)

Authors

Guy Nason [aut, cre]

Initial release

2016-10-18