GRAPHMAP - Convert binary map to connected graph and reciprocally.

Contents

Syntax (i)

     map = GRAPHMAP(graph, vertex);
     map = GRAPHMAP(graph, vertex, domain);

Converts a spatial (undirected) graph (given by the adjacency matrix graph and the set of vertices vertex) into a 2D logical map (whose domain may be defined in domain as a vector [xend,yend,x0,y0,xstep,ystep]) with pixels connecting the vertices of the graph through straight lines set to true. Straight lines between vertices are approximated using Bresenham's algorithm. See function GRAPH2MAP_BASE.

Syntax (ii)

     [graph, vertex] = GRAPHMAP(map, weight);
     [graph, vertex] = GRAPHMAP(map, weight, conn);

Converts a spatial 2D logical map with true pixels belonging to a (connected) network into an (undirected) weighted graph, whose weights are possibly passed as an additional weight map. See function MAP2GRAPH_BASE.

See also

Ressembles: FILLNETWORK, BRESENHAMLINE. Requires: MAP2GRAPH_BASE, GRAPH2MAP_BASE.

Function implementation

function [O1, O2] = graphmap(varargin)

parsing parameters

error(nargchk(3, 11, nargin, 'struct'));
error(nargoutchk(1, 2, nargout, 'struct'));

p = createParser('GRAPHMAP');
% mandatory parameters
p.addRequired('I1', @(x)isnumeric(x) || islogical(x) || issparse(x)); % map or graph
p.addRequired('I2', @(x)isnumeric(x)); % weight or vertex
p.addOptional('I3', [], @(x)(isvector(x) && length(x)<=6) || ...
    (isscalar(x) && ismember(x,[4,8]))); % conn or domain

% parse and validate all input arguments
p.parse(varargin{:});
p = getvarParser(p);

checking/setting parameters

[m1,n1] = size(p.I1);
[m2,n2] = size(p.I2);
isamap = isequal([m1,n1],[m2,n2]);

if isnumeric(p.I1)
    if ~(isamap || (m1==n1 && n2==2))
        error('graphmap:inputerror','incompatible input parameters');
    end
    p.I1 = sparse(logical(p.I1)); % in both cases, we reduce the complexity
end

if isempty(p.I3)
    if isamap % we are converting a map
        p.I3 = 8;

    else
        p.I3 = [max(p.I2(:,1)) max(p.I2(:,2))... % (X,Y) sizes
            min(p.I2(:,1)) min(p.I2(:,2))  ... % (X,Y) origins
            1 1]; % default steps size
        % note here that we haven't tested that p.I2 is a vertex matrix,
        % but we'll do it aftwewards
    end
end

% test again, in the case some variables have been passed
if isamap
    if ~(m1==m2 && n1==n2)
        error('graphmap:inputerror',...
            'incompatible map and weight matrices'' dimensions');
    elseif ~isscalar(p.I3)
        error('graphmap:inputerror',...
            '3rd input must be connectivity index {4,8} ');
    end

else
    if m1~=m2
        error('graphmap:inputerror',...
            'square input adjacency matrix required');
    elseif n2~=2 || m1>m2
        error('graphmap:inputerror',...
            'incompatible graph and vertices indices');
    elseif ~isvector(p.I3)
        error('graphmap:inputerror',...
            '3rd input must be a domain definition vector');
    end

end

main calculation

if isamap
    [O1, ... %graph
        O2] ... %vertex
        = map2graph_base(p.I1, ... %map
        p.I2, ... %weight
        p.I3); %connectivity

else
    O1 ... %map
        = graph2map_base(p.I1, ... %graph
        p.I2, ... %vertex
        p.I3); %domain
    O2 = []; % TODO: implement the wweight
end

end % end of graphmap