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function wt = wfbtremove(d,kk,wt,varargin)
%-*- texinfo -*-
%@deftypefn {Function} wfbtremove
%@verbatim
%WFBTREMOVE Remove node(s) from the filterbank tree
% Usage: wt = wbftremove(d,kk,wt);
% wt = wfbtremove(d,kk,wt,'force');
%
% Input parameters:
% d : Level in the tree (0 - root).
% kk : Index of the node at level d (starting at 0) or array
% of indexes.
% wt : Wavelet filterbank tree structure (as returned from
% WFBTINIT).
%
% Output parameters:
% wt : Modified filterbank structure.
%
% WFBTREMOVE(d,kk,wt) removes existing node at level d and index kk*
% from the filterbank tree structure wt. The function fails if the
% node has any children (it is not a leaf node).
%
% WFBTREMOVE(d,k,wt,'force') does the same, but any childern of the
% node are removed too.
%
% Examples:
% ---------
%
% The following example shows magnitude frequency responses of filterbank
% tree before and after prunning.:
%
% % Create a full filterbank tree usinf 'db10' basic filterbank.
% wt1 = wfbtinit({'db10',4,'full'});
% % Remove a subtree starting by root's high-pass filter. Force flag
% % is used because we are removing a non-leaf node.
% wt2 = wfbtremove(1,1,wt1,'force');
%
% % Create identical filterbanks
% [g1,a1] = wfbt2filterbank(wt1,'freq');
% [g2,a2] = wfbt2filterbank(wt2,'freq');
%
% % Plot the frequency responses
% subplot(2,1,1);
% filterbankfreqz(g1,a1,1024,'plot','posfreq','linabs');
% subplot(2,1,2);
% filterbankfreqz(g2,a2,1024,'plot','posfreq','linabs');
%
%
%@end verbatim
%@strong{Url}: @url{http://ltfat.github.io/doc/wavelets/wfbtremove.html}
%@end deftypefn
% Copyright (C) 2005-2016 Peter L. Soendergaard <peter@sonderport.dk>.
% This file is part of LTFAT version 2.3.1
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
% AUTHOR: Zdenek Prusa
complainif_notenoughargs(nargin,3,'WFBTREMOVE');
definput.flags.force = {'noforce','force'};
flags=ltfatarghelper({},definput,varargin);
if isempty(wt.nodes)
error('%s: Tree is empty.',mfilename);
end
for k=kk
[nodeNo,nodeChildIdx] = depthIndex2NodeNo(d,k,wt);
if(nodeNo==0)
% removing root
rootNo = find(wt.parents==0);
% check for any children of the root
if any(wt.children{rootNo}~=0) && ~flags.do_force
error(['%s: Deleting root node. To delete the whole tree ',...
'use FORCE option.'],mfilename,d,k);
else
wt = nodeSubtreeDelete(rootNo,wt);
continue;
end
end
% check if node exists
childrenIdx = find(wt.children{nodeNo}~=0);
found = find(childrenIdx==nodeChildIdx,1);
if(isempty(found))
error('%s: Such node (depth=%d, idx=%d) does not exist.',mfilename,d,k);
end
nodeToDelete = wt.children{nodeNo}(nodeChildIdx);
% Check if it is a leaf (terminal node)
if any(wt.children{nodeToDelete}~=0) && ~flags.do_force
error(['%s: Deleting a non-leaf node. To delete whole subtree use ',...
'FORCE option.'],mfilename);
else
wt = nodeSubtreeDelete(nodeToDelete,wt);
end
end
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