diff _misc/general/.svn/text-base/dpfast.m.svn-base @ 8:b5b38998ef3b

added all that other stuff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/_misc/general/.svn/text-base/dpfast.m.svn-base	Fri Apr 11 15:54:25 2014 +0100
@@ -0,0 +1,92 @@
+function [p,q,D,sc] = dpfast(M,C,T,G)
+% [p,q,D,sc] = dpfast(M,C,T,G) 
+%    Use dynamic programming to find a min-cost path through matrix M.
+%    Return state sequence in p,q; full min cost matrix as D and 
+%    local costs along best path in sc.
+%    This version gives the same results as dp.m, but uses dpcore.mex
+%    to run ~200x faster.
+%    C is a step matrix, with rows (i step, j step, cost factor)
+%    Default is [1 1 1.0;0 1 1.0;1 0 1.0];
+%    Another good one is [1 1 1;1 0 1;0 1 1;1 2 2;2 1 2]
+%    T selects traceback origin: 0 is to any edge; 1 is top right (default);
+%    T > 1 finds path to min of anti-diagonal T points away from top-right.
+%    Optional G defines length of 'gulleys' for T=0 mode; default 0.5
+%    (i.e. accept path to only 50% of edge nearest top-right)
+% 2003-04-04,2005-04-04 [e-mail] $Header: /Users/dpwe/projects/dtw/RCS/dpfast.m,v 1.6 2008/03/14 14:40:50 dpwe Exp $
+
+% Copyright (c) 2003 Dan Ellis <[e-mail]>
+% released under GPL - see file COPYRIGHT
+
+if nargin < 2
+  % Default step / cost matrix
+  C = [1 1 1.0;0 1 1.0;1 0 1.0];
+end
+
+if nargin < 3
+  % Default: path to top-right
+  T = 1;
+end
+
+if nargin < 4
+  % how big are gulleys?
+  G = 0.5;  % half the extent
+end
+
+if sum(isnan(M(:)))>0
+  error('dpwe:dpfast:NAN','Error: Cost matrix includes NaNs');
+end
+
+if min(M(:)) < 0
+  disp('Warning: cost matrix includes negative values; results may not be what you expect');
+end
+
+[r,c] = size(M);
+
+% Core cumulative cost calculation coded as mex
+[D,phi] = dpcore(M,C);
+
+p = [];
+q = [];
+
+%% Traceback from top left?
+%i = r; 
+%j = c;
+
+if T == 0
+  % Traceback from lowest cost "to edge" (gulleys)
+  TE = D(r,:);
+  RE = D(:,c);
+  % eliminate points not in gulleys
+  TE(1:round((1-G)*c)) = max(max(D));
+  RE(1:round((1-G)*r)) = max(max(D));
+  if (min(TE) < min(RE))
+    i = r;
+    j = max(find(TE==min(TE)));
+  else
+    i = max(find(RE==min(RE)));
+    j = c;
+  end
+else
+  % Traceback from min of antidiagonal
+  %stepback = floor(0.1*c);
+  stepback = T;
+  slice = diag(fliplr(D),-(r-stepback));
+  [mm,ii] = min(slice);
+  i = r - stepback + ii;
+  j = c + 1 - ii;
+end
+
+p=i;
+q=j;
+
+sc = M(p,q);
+
+while i > 1 & j > 1
+%  disp(['i=',num2str(i),' j=',num2str(j)]);
+  tb = phi(i,j);
+  i = i - C(tb,1);
+  j = j - C(tb,2);
+  p = [i,p];
+  q = [j,q];
+  sc = [M(i,j),sc];
+end