Mercurial > forge
view extra/tsa/inst/histo3.m @ 12524:3d8947eadc0e octave-forge
histo[234]: empty imput is supported, add tests
author | schloegl |
---|---|
date | Tue, 23 Sep 2014 00:39:17 +0000 |
parents | 430712382527 |
children | 0b91f4c42213 |
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function [R, tix] = histo3(Y, W) % HISTO3 calculates histogram for multiple columns with common bin values % among all data columns, and can be useful for data compression. % % R = HISTO3(Y) % R = HISTO3(Y, W) % Y data % W weight vector containing weights of each sample, % number of rows of Y and W must match. % default W=[] indicates that each sample is weighted with 1. % R struct with these fields % R.X the bin-values, bin-values are equal for each channel % thus R.X is a column vector. If bin values should % be computed separately for each data column, use HISTO2 % R.H is the frequency of occurence of value X % R.N are the number of valid (not NaN) samples % % Data compression can be performed in this way % [R,tix] = histo3(Y) % is the compression step % % R.tix provides a compressed data representation. % R.compressionratio estimates the compression ratio % % R.X(tix) and R.X(R.tix) % reconstruct the orginal signal (decompression) % % The effort (in memory and speed) for compression is O(n*log(n)). % The effort (in memory and speed) for decompression is O(n) only. % % see also: HISTO, HISTO2, HISTO3, HISTO4 % % REFERENCE(S): % C.E. Shannon and W. Weaver "The mathematical theory of communication" University of Illinois Press, Urbana 1949 (reprint 1963). % $Id$ % Copyright (C) 1996-2002,2008,2011,2014 by Alois Schloegl <alois.schloegl@ist.ac.at> % This is part of the TSA-toolbox. See also % http://pub.ist.ac.at/~schloegl/matlab/tsa/ % http://octave.sourceforge.net/ % http://biosig.sourceforge.net/ % % 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/>. %%%%% check input arguments %%%%% [yr,yc] = size(Y); if nargin < 2, W = []; end; if ~isempty(W) && (yr ~= numel(W)), error('number of rows of Y does not match number of elements in W'); end; %%%%% identify all possible X's and generate overall Histogram %%%%% [sY, idx] = sort(Y(:),1); [tmp,idx1] = sort(idx); % generate inverse index ix = diff(sY, [], 1) > 0; tmp = [find(ix); sum(~isnan(sY))]; R.datatype = 'HISTOGRAM'; R.N = sum(~isnan(Y), 1); if all(R.N==0) R.X=[]; R.H=[]; return; end; R.X = sY(tmp); % generate inverse index if nargout>1, tix = cumsum([1; ix]); % rank tix = reshape(tix(idx1), yr, yc); % inverse sort rank cc = 1; tmp = sum(ix) + 1; if exist('OCTAVE_VERSION') >= 5, ; % NOP; no support for integer datatyp elseif tmp <= 2^8; tix = uint8(tix); cc = 8/1; elseif tmp <= 2^16; tix = uint16(tix); cc = 8/2; elseif tmp <= 2^32; tix = uint32(tix); cc = 8/4; end; R.compressionratio = (prod(size(R.X)) + (yr*yc)/cc) / (yr*yc); R.tix = tix; end; if yc==1, if isempty(W) R.H = [tmp(1); diff(tmp)]; else C = cumsum(W(idx)); % cumulative weights R.H = [C(tmp(1)); diff(C(tmp))]; end; return; elseif yc>1, % allocate memory H = zeros(size(R.X,1),yc); % scan each channel for k = 1:yc, if isempty(W) sY = sort(Y(:,k)); else [sY,ix] = sort(Y(:,k)); C = cumsum(W(ix)); end ix = find(diff(sY,[],1) > 0); if size(ix,1) > 0, tmp = [ix; R.N(k)]; else tmp = R.N(k); end; t = 0; j = 1; if isempty(W) for x = tmp', acc = sY(x); while R.X(j)~=acc, j=j+1; end; %j = find(sY(x)==R.X); % identify position on X H(j,k) = H(j,k) + (x-t); % add diff(tmp) t = x; end; else for x = tmp', acc = sY(x); while R.X(j)~=acc, j=j+1; end; %j = find(sY(x)==R.X); % identify position on X H(j,k) = H(j,k) + C(x)-t; % add diff(tmp) t = C(x); end; end; end; R.H = H; end; %!assert(getfield(histo3([]),'N'), 0) %!assert(getfield(histo3(1),'N'), 1) %!assert(getfield(histo3([1;1]),'H'), 2)