Daniel@0: function rte = pred2path(P,s,t)
Daniel@0: %PRED2PATH Convert predecessor indices to shortest paths from node 's' to 't'.
Daniel@0: %   rte = pred2path(P,s,t)
Daniel@0: %     P = |s| x n matrix of predecessor indices (from DIJK)
Daniel@0: %     s = FROM node indices
Daniel@0: %       = [] (default), paths from all nodes
Daniel@0: %     t = TO node indices
Daniel@0: %       = [] (default), paths to all nodes
Daniel@0: %   rte = |s| x |t| cell array of paths (or routes) from 's' to 't', where
Daniel@0: %         rte{i,j} = path from s(i) to t(j)
Daniel@0: %                  = [], if no path exists from s(i) to t(j)
Daniel@0: %
Daniel@0: % (Used with output of DIJK)
Daniel@0: 
Daniel@0: % Copyright (c) 1998-2001 by Michael G. Kay
Daniel@0: % Matlog Version 5 22-Aug-2001
Daniel@0: 
Daniel@0: % Input Error Checking ******************************************************
Daniel@0: error(nargchk(1,3,nargin));
Daniel@0: 
Daniel@0: [rP,n] = size(P);
Daniel@0: 
Daniel@0: if nargin < 2 | isempty(s), s = (1:n)'; else s = s(:); end
Daniel@0: if nargin < 3 | isempty(t), t = (1:n)'; else t = t(:); end
Daniel@0: 
Daniel@0: if any(P < 0 | P > n)
Daniel@0:    error(['Elements of P must be integers between 1 and ',num2str(n)]);
Daniel@0: elseif any(s < 1 | s > n)
Daniel@0:    error(['''s'' must be an integer between 1 and ',num2str(n)]);
Daniel@0: elseif any(t < 1 | t > n)
Daniel@0:    error(['''t'' must be an integer between 1 and ',num2str(n)]);
Daniel@0: end
Daniel@0: % End (Input Error Checking) ************************************************
Daniel@0: 
Daniel@0: rte = cell(length(s),length(t));
Daniel@0: 
Daniel@0: for i = 1:length(s)
Daniel@0:    if rP == 1
Daniel@0:       si = 1;
Daniel@0:    else
Daniel@0:       si = s(i);
Daniel@0:       if si < 1 | si > rP
Daniel@0:          error('Invalid P matrix.')
Daniel@0:       end
Daniel@0:    end
Daniel@0:    for j = 1:length(t)
Daniel@0:       tj = t(j);
Daniel@0:       if tj == s(i)
Daniel@0:          r = tj;
Daniel@0:       elseif P(si,tj) == 0
Daniel@0:          r = [];
Daniel@0:       else
Daniel@0:          r = tj;
Daniel@0:          while tj ~= s(i)
Daniel@0:             if tj < 1 | tj > n
Daniel@0:                error('Invalid element of P matrix found.')
Daniel@0:             end
Daniel@0:             r = [P(si,tj) r];
Daniel@0:             tj = P(si,tj);
Daniel@0:          end
Daniel@0:       end
Daniel@0:       rte{i,j} = r;
Daniel@0:    end
Daniel@0: end
Daniel@0: 
Daniel@0: if length(s) == 1 & length(t) == 1
Daniel@0:    rte = rte{:};
Daniel@0: end
Daniel@0: 
Daniel@0: %rte = t;
Daniel@0: while 0%t ~= s
Daniel@0:    if t < 1 | t > n | round(t) ~= t
Daniel@0:       error('Invalid ''pred'' element found prior to reaching ''s''');
Daniel@0:    end
Daniel@0:    rte = [P(t) rte];
Daniel@0:    t = P(t);
Daniel@0: end
Daniel@0: