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function rayOrder = createOrderART(proj_geom, mode)
%------------------------------------------------------------------------
% rayOrder = createOrderART(proj_geom, mode)
%
% Creates an array defining the order in which ART will iterate over the
% projections and projection rays
%
% proj_geom: MATLAB struct containing the projection geometry.
% mode: string defining the wanted ray order, can be either 'sequential',
% 'randomray' or 'randomproj'.
% rayOrder: array of two columns of length angle_count * det_count, with
% the first column being the index of the projection and the second column
% the index of the ray.
%------------------------------------------------------------------------
%------------------------------------------------------------------------
% This file is part of the ASTRA Toolbox
%
% Copyright: 2010-2021, imec Vision Lab, University of Antwerp
% 2014-2021, CWI, Amsterdam
% License: Open Source under GPLv3
% Contact: astra@astra-toolbox.com
% Website: http://www.astra-toolbox.com/
%------------------------------------------------------------------------
angle_count = length(proj_geom.projection_angles);
det_count = proj_geom.detector_count;
% create order
rayOrder = zeros(angle_count * det_count, 2);
if strcmp(mode,'sequential') == 1
index = 1;
for i = 1:angle_count
for j = 1:det_count
rayOrder(index,1) = i;
rayOrder(index,2) = j;
index = index + 1;
end
end
elseif strcmp(mode,'randomray') == 1
index = 1;
for i = 1:angle_count
for j = 1:det_count
rayOrder(index,1) = i;
rayOrder(index,2) = j;
index = index + 1;
end
end
r = randperm(angle_count * det_count);
rayOrder(:,1) = rayOrder(r,1);
rayOrder(:,2) = rayOrder(r,2);
elseif strcmp(mode,'randomproj') == 1
index = 1;
r = randperm(angle_count);
for i = 1:angle_count
for j = 1:det_count
rayOrder(index,1) = r(i);
rayOrder(index,2) = j;
index = index + 1;
end
end
else
disp('mode not known');
end
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