LARGESTR Keep fixed ratio of largest coefficients
Usage: xo=largestr(x,p);
xo=largestr(x,p,mtype);
[xo,N]=largestr(...);
LARGESTR(x,p) returns an array of the same size as x keeping
the fraction p of the coefficients. The coefficients with the largest
magnitude are kept.
[xo,n]=LARGESTR(xi,p) additionally returns the number of coefficients
kept.
*Note:* If the function is used on coefficients coming from a
redundant transform or from a transform where the input signal was
padded, the coefficient array will be larger than the original input
signal. Therefore, the number of coefficients kept might be higher than
expected.
LARGESTR takes the following flags at the end of the line of input
arguments:
'hard' Perform hard thresholding. This is the default.
'wiener' Perform empirical Wiener shrinkage. This is in between
soft and hard thresholding.
'soft' Perform soft thresholding.
'full' Returns the output as a full matrix. This is the default.
'sparse' Returns the output as a sparse matrix.
*Note:* If soft- or Wiener thresholding is selected, one less
coefficient will actually be returned. This is caused by that
coefficient being set to zero.
References:
S. Mallat. A wavelet tour of signal processing. Academic Press, San
Diego, CA, 1998.
Url: http://ltfat.github.io/doc/sigproc/largestr.html
See also: largestn.
Package: ltfat