| accessD.mwd {wavethresh} | R Documentation |
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.
accessD.mwd(mwd, level, ...)
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 |
The mwd function produces a multiple wavelet decomposition object .
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 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.
A matrix with mwd$filter$npsi rows containing the extracted coefficients.
Tim Downie 1995-6
accessD.mwd, draw.mwd, mfirst.last, mfilter.select, mwd, mwd.object, plot.mwd, print.mwd, putC.mwd, putD.mwd, summary.mwd, threshold.mwd, wd, wr.mwd
# # Get the 3rd level of smoothed data from a decomposition # data(ipd) accessD.mwd(mwd(ipd), level=3)