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Slepi/Code/Utilities/gspbox/graphs/gsp_sensor.m
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gsp_sensor.m
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function G = gsp_sensor(N, param)
%GSP_SENSOR Create a random sensor graph
% Usage: G = gsp_sensor(N);
% G = gsp_sensor( );
% G = gsp_sensor(N, param);
%
% Input parameters
% - N : Number of nodes (default 128)
% - param : Structure of optional parameters
% Output parameters
% - G : Graph
%
% This function creates a 2 dimensional random sensor graph. All the
% coordinates are between 0 and 1.
%
% param is an optional structure with the following field
%
% param.verbose*: display parameter - 0 no log - 1 display the errors (default 1)
% param.N_try*: Number of attempts to create the graph (default 10)
% param.distribute*: To distribute the points more evenly (default 0)
% param.connected*: To force the graph to be connected (default 1)
% param.nnparam*: optional parameter for the gsp_nn_graph
%
%
% Example:
%
% G = gsp_sensor(300);
% paramplot.show_edges = 1;
% gsp_plot_graph(G,paramplot);
%
%
% Url: http://lts2research.epfl.ch/gsp/doc/graphs/gsp_sensor.php
% Copyright (C) 2013-2016 Nathanael Perraudin, Johan Paratte, David I Shuman.
% This file is part of GSPbox version 0.5.2
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
% If you use this toolbox please kindly cite
% N. Perraudin, J. Paratte, D. Shuman, V. Kalofolias, P. Vandergheynst,
% and D. K. Hammond. GSPBOX: A toolbox for signal processing on graphs.
% ArXiv e-prints, Aug. 2014.
% http://arxiv.org/abs/1408.5781
% Date: 6 june 2013
% Author: Nathanael Perraudin
if nargin < 2
param = struct;
end
if nargin < 1
N = 64;
end
if N<6
error('N needs to be greater than 6')
end
if ~isfield(param, 'verbose'), param.verbose = 1; end
if ~isfield(param, 'N_try'), param.N_try = 10; end
if ~isfield(param, 'distribute'), param.distribute = 0; end
if ~isfield(param, 'connected'), param.connected = 1; end
if ~isfield(param, 'nnparam'), param.nnparam = {}; end
if ~isfield(param.nnparam, 'k'), param.nnparam.k = 6; end
if param.connected
for n=1:param.N_try
[ XCoords, YCoords] = create_coords(N,param.distribute);
% sort rows for plotting reasons
G = gsp_nn_graph(sortrows([XCoords, YCoords]),param.nnparam);
if gsp_check_connectivity(G)
break;
elseif n == param.N_try
fprintf('Warning! Graph is not connected\n');
end
end
else
[ XCoords, YCoords] = create_coords(N,param.distribute);
% sort rows for plotting reasons
G = gsp_nn_graph(sortrows([XCoords, YCoords]),param.nnparam);
end
% Return the values
G.type = 'sensor';
G = gsp_graph_default_parameters(G);
end
function [ XCoords, YCoords] = create_coords(N, distribute)
% TODO: VECTORIZE!!!!
XCoords = zeros(N,1);
YCoords = zeros(N,1);
if distribute
mdim = ceil(sqrt(N));
ind = 1;
for ii = 0:mdim-1
for jj=0:mdim-1
if ind<=N
XCoords(ind) = 1/mdim*rand(1)+ii*1/mdim;
YCoords(ind) = 1/mdim*rand(1)+jj*1/mdim;
end
ind = ind+1;
end
end
else
% take random coordinates in a 1 by 1 square
XCoords = rand(N,1);
YCoords = rand(N,1);
end
end
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