Description of sledges2adjmat

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sledges2adjmat

PURPOSE

SLEDGES2ADJMAT Creates an adjacency matrix from edge set

SYNOPSIS

function A = sledges2adjmat(n, nt, edges, varargin)

DESCRIPTION

SLEDGES2ADJMAT Creates an adjacency matrix from edge set

 $ Syntax $
   - A = sledges2adjmat(n, nt, edges, ...)

 $ Arguments $
   - n:            The number of (source) nodes
   - nt:           The number of (target) nodes
   - edges:        The matrix of edge set
   
 $ Description $
   - A = sledges2adjmat(n, nt, edges) creates an adjacency matrix 
     from the edge set. You can specify the following properties:
       - 'valtype':        the value type of the target matrix
                           - 'auto': if has value, make numeric matrix
                                     if no value, make logical matrix
                           - 'logical': make logical matrix always
                           - 'numeric': make numeric matrix always
                           (default = 'auto')
       - 'sparse':         whether to create a sparse matrix 
                           (default = true)
       - 'preprune':       whether to prune the edges first 
                           (default = false)
       - 'prunemethod':    the method used to prune the edge set
                           (default = [], means using default method)
                           refer to slpruneedgeset for the specification 
                           of the prune methods.
       - 'sym':            whether to create symmetric graph
       - 'symmethod':      the method to symmetrize the graph
                           (default = [], means using default method)
                           refer to slsymedgeset for the specification.

 $ Remarks $
   - The property sym can only be true when n == nt.

   - It is an integrated wrapper for slmakeadjmat, slsymgraph and
     slpruneedgeset.

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

CROSS-REFERENCE INFORMATION

This function calls:

• slmakeadjmat SLMAKEADJMAT Makes an adjacency matrix using edges and corresponing values
• slpruneedgeset SLPRUNEEDGESET Prunes the edge set
• slsymgraph SLSYMGRAPH Forces symmetry of the adjacency matrix of a graph
• raise_lackinput RAISE_LACKINPUT Raises an error indicating lack of input argument
• slparseprops SLPARSEPROPS Parses input parameters

This function is called by:

• sladjmat SLADJMAT Constructs the adjacency matrix representation of a graph

SOURCE CODE

0001 function A = sledges2adjmat(n, nt, edges, varargin)
0002 %SLEDGES2ADJMAT Creates an adjacency matrix from edge set
0003 %
0004 % $ Syntax $
0005 %   - A = sledges2adjmat(n, nt, edges, ...)
0006 %
0007 % $ Arguments $
0008 %   - n:            The number of (source) nodes
0009 %   - nt:           The number of (target) nodes
0010 %   - edges:        The matrix of edge set
0011 %
0012 % $ Description $
0013 %   - A = sledges2adjmat(n, nt, edges) creates an adjacency matrix
0014 %     from the edge set. You can specify the following properties:
0015 %       - 'valtype':        the value type of the target matrix
0016 %                           - 'auto': if has value, make numeric matrix
0017 %                                     if no value, make logical matrix
0018 %                           - 'logical': make logical matrix always
0019 %                           - 'numeric': make numeric matrix always
0020 %                           (default = 'auto')
0021 %       - 'sparse':         whether to create a sparse matrix
0022 %                           (default = true)
0023 %       - 'preprune':       whether to prune the edges first
0024 %                           (default = false)
0025 %       - 'prunemethod':    the method used to prune the edge set
0026 %                           (default = [], means using default method)
0027 %                           refer to slpruneedgeset for the specification
0028 %                           of the prune methods.
0029 %       - 'sym':            whether to create symmetric graph
0030 %       - 'symmethod':      the method to symmetrize the graph
0031 %                           (default = [], means using default method)
0032 %                           refer to slsymedgeset for the specification.
0033 %
0034 % $ Remarks $
0035 %   - The property sym can only be true when n == nt.
0036 %
0037 %   - It is an integrated wrapper for slmakeadjmat, slsymgraph and
0038 %     slpruneedgeset.
0039 %
0040 % $ History $
0041 %   - Created by Dahua Lin, on Sep 9, 2006
0042 %
0043 
0044 %% parse and verify input arguments
0045 
0046 if nargin < 3
0047     raise_lackinput('sledges2adjmat', 3);
0048 end
0049 
0050 if ~isempty(edges)
0051     ncols = size(edges, 2);
0052     if ndims(edges) ~= 2 || (ncols ~= 2 && ncols ~= 3)
0053         error('sltoolbox:invalidarg', ...
0054             'The edges should be a 2D matrix with two or three columns');
0055     end
0056 end
0057 
0058 opts.valtype = 'auto';
0059 opts.sparse = true;
0060 opts.preprune = false;
0061 opts.prunemethod = [];
0062 opts.sym = false;
0063 opts.symmethod = [];
0064 opts = slparseprops(opts, varargin{:});
0065 
0066 if opts.sym
0067     if n ~= nt
0068         error('sltoolbox:rterror', ...
0069             'The sym can only be true when n == nt');
0070     end
0071 end
0072 
0073 switch opts.valtype
0074     case 'auto'
0075         islogic = (ncols == 2);
0076     case 'numeric'
0077         islogic = false;
0078     case 'logical'
0079         islogic = true;
0080     otherwise
0081         error('sltoolbox:invalidarg', ...
0082         'Invalid value type of adjacency matrix: %s', opts.valtype);
0083 end
0084 
0085 
0086 %% main skeleton
0087 
0088 % prune
0089 if opts.preprune
0090     edges = slpruneedgeset(n, nt, edges, opts.prunemethod);
0091 end
0092 
0093 % make adjmat
0094 
0095 A = slmakeadjmat(n, nt, edges, [], islogic, opts.sparse);
0096 
0097 % symmetrize
0098 if opts.sym
0099     A = slsymgraph(A, opts.symmethod);
0100 end
0101

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