Description of sladjlist

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sladjlist

PURPOSE

SLADJLIST Construct the adjacency list representation of a graph

SYNOPSIS

function Gd = sladjlist(G, uv)

DESCRIPTION

SLADJLIST Construct the adjacency list representation of a graph

 $ Syntax $
   - Gd = sladjlist(G)
   - Gd = sladjlist(G, uv)

 $ Arguments $
   - G:        The input graph (or bigraph)
   - Gd:       The output adjacency list representation of the graph
   - uv:       The using-value scheme

 $ Description $
   - Gd = sladjlist(G) constructs the adjacency list representation of the
     graph G with an automatic selection of uv scheme.

   - Gd = sladjlist(G, uv) constructs the adjacency list representation of 
     the graph G with a specified uv scheme.
     There are the following uv schems:
       - 'auto':   automatic selection (default)
                   If G has values then use the values for construction,
                   otherwise not use.
       - 'on':     force to use values, if G has no values then assign
                   1 to all edges
       - 'off':    force not to use values even if G has values.

 $ History $
   - Created by Dahua Lin, on Sep 9, 2006

CROSS-REFERENCE INFORMATION

This function calls:

• sledgeset2adjlist SLEDGESET2ADJLIST Converts edge set to adjacency list
• slgraphinfo SLGRAPHINFO Extracts basic information of a given graph representation

This function is called by:

SOURCE CODE

0001 function Gd = sladjlist(G, uv)
0002 %SLADJLIST Construct the adjacency list representation of a graph
0003 %
0004 % $ Syntax $
0005 %   - Gd = sladjlist(G)
0006 %   - Gd = sladjlist(G, uv)
0007 %
0008 % $ Arguments $
0009 %   - G:        The input graph (or bigraph)
0010 %   - Gd:       The output adjacency list representation of the graph
0011 %   - uv:       The using-value scheme
0012 %
0013 % $ Description $
0014 %   - Gd = sladjlist(G) constructs the adjacency list representation of the
0015 %     graph G with an automatic selection of uv scheme.
0016 %
0017 %   - Gd = sladjlist(G, uv) constructs the adjacency list representation of
0018 %     the graph G with a specified uv scheme.
0019 %     There are the following uv schems:
0020 %       - 'auto':   automatic selection (default)
0021 %                   If G has values then use the values for construction,
0022 %                   otherwise not use.
0023 %       - 'on':     force to use values, if G has no values then assign
0024 %                   1 to all edges
0025 %       - 'off':    force not to use values even if G has values.
0026 %
0027 % $ History $
0028 %   - Created by Dahua Lin, on Sep 9, 2006
0029 %
0030 
0031 %% parse and verify input
0032 
0033 gi = slgraphinfo(G);
0034 
0035 if nargin < 2 || isempty(uv)
0036     uv = 'auto';
0037 end
0038 
0039 
0040 %% decide scheme
0041 % sch:
0042 %   0:  no value -> no value
0043 %   1:  no value -> has value
0044 %   2:  has value -> no value
0045 %   3:  has value -> has value
0046 
0047 switch uv
0048     case 'auto'
0049         if gi.valued
0050             sch = 3;
0051         else
0052             sch = 0;
0053         end
0054     case 'on'
0055         if gi.valued
0056             sch = 3;
0057         else
0058             sch = 1;
0059         end
0060     case 'off'
0061         if gi.valued
0062             sch = 2;
0063         else
0064             sch = 0;
0065         end
0066     otherwise
0067         error('sltoolbox:invalidarg', ...
0068             'Invalid using-value scheme: %s', uv);
0069 end
0070 
0071 %% do construction
0072 
0073 switch gi.type
0074     case 'ge'
0075         Gd = struct('n', gi.n);
0076     case 'bi'
0077         Gd = struct('n', gi.n, 'nt', gi.nt);
0078 end
0079 
0080 switch gi.form
0081     case 'edgeset'
0082         Gd.targets = sledgeset2adjlist(G.n, G.edges, sch);
0083         
0084     case 'adjlist'
0085         switch sch
0086             case {0, 3}
0087                 Gd.targets = G.targets;
0088             case 1
0089                 Gd.targets = cell(size(G.targets));
0090                 nc = numel(G.targets);
0091                 for i = 1 : nc
0092                     ci = G.targets{i};                  
0093                     if ~isempty(ci)
0094                         cn = size(ci, 1);
0095                         ci = [ci, ones(cn,1)];
0096                         Gd.targets{i} = ci;
0097                     end
0098                 end
0099             case 2
0100                 Gd.targets = cell(size(G.targets));
0101                 nc = numel(G.targets);
0102                 for i = 1 : nc
0103                     ci = G.targets{i};                  
0104                     if ~isempty(ci)
0105                         Gd.targets{i} = ci(:, 1);
0106                     end
0107                 end
0108         end
0109         
0110     case 'adjmat'
0111         if gi.valued
0112             [I, J, V] = find(G);
0113             edges = [I, J, V];
0114             clear I J V;
0115         else
0116             [I, J] = find(G);
0117             edges = [I, J];
0118             clear I J;
0119         end
0120         Gd.targets = sledgeset2adjlist(size(G,1), edges, sch);
0121 end
0122 
0123             
0124                 
0125 
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