Partition Portions of N-D Arrays in Matlab using either a center of a region or corner of a region as a reference.

partition_space.m

function part = partition_space( Data,varargin );
% Remove subsets of information from large volumetric images
% Two options
% # ``corner`` <<default>> - Reference position is the top left corner of
% the image.
%         ``window`` - is a vector where each element defines the window
%         size in a given direction
% # ``center`` -  the center of the iamge
%         ``window`` - is a column vector where each row is the dimension
%         of the array and the first a distance less than the center and
%         the second column is a right greater than the center in its
%         respecitve dimension.
%                   'window, [-10 10;
%                             -2 31]
%                   A window 10 left to 10 right of center(1)  &
%                   A window -2 left to 31 right of center(2)


OSZ = size( Data );
DIM = ndims( Data );

param = setparam( OSZ, DIM, varargin{:} );

switch param.type
    case 'center'
        param.args.center(numel(param.args.center)+1:3) = 1;
        if isvector( param.args.center )
            lastid = 1;
        else
            lastid = size( param.args.center,1);
        end
        for ii = 1 : lastid
            tempargs = struct( 'center', param.args.center(ii,:), ...
                               'window', param.args.window );
            v{ii} = cntr_args2vec( tempargs, OSZ );
        end
    case 'box'
        % For linspace
        param.args.corner(numel(param.args.corner)+1:3) = 1;
        if isvector( param.args.corner )
            lastid = 1;
        else
            lastid = size( param.args.corner,1);
        end
        for ii = 1 : lastid
            tempargs = struct( 'corner', param.args.corner(ii,:), ...
                               'window', param.args.window );
            v{ii} = box_args2vec( tempargs, OSZ );
        end
end

part = cellfun( @(v) Data( v{1}, v{2}, v{3} ), v , 'UniformOutput',false );
if numel( part ) == 1
    part = part{1};
end

end % partition_space
%%
function vec = box_args2vec( args, OSZ )
% Express the window limits as vector

for ii = 1 : 3
    vec{ii} = [1 : args.window(ii) ] + args.corner(ii) - 1;
    vec{ii}( vec{ii} < 1 | vec{ii} > OSZ(ii) ) = [];
end % for ii

end % box_args2vec

function vec = cntr_args2vec( args, OSZ )
% Express the window limits as vector

for ii = 1 : 3
    vec{ii} = [args.window(ii,1) : args.window(ii,2) ] + args.center(ii);
    vec{ii}( vec{ii} < 1 | vec{ii} > OSZ(ii) ) = [];
end % for ii

end % cntr_args2vec

function param = setparam( OSZ, DIM, varargin )
% Set function parameters

param = struct( 'type', 'box' ,...
                'args',  struct( 'corner', [1 1 1], ...
                'window',[10 10 10] ) );
          
for ii = 1 : 2 : numel(varargin)
    switch varargin{ii}
        case 'corner'
            param = struct( 'type', 'box' ,...
                'args',  struct( 'corner', [1 1 1], ...
                'window',[10 10 10] ) );
        case 'center'
            param = struct( 'type', 'center' ,...
                'args', struct( 'center', [1 1 1], ...
                'window',[-10 10 ; -10 10; -10 10] ) );
    end % switch varargin
end % for ii

for ii = 1 : 2 : numel(varargin)
    if ismember( varargin{ii} , {'corner', 'window', 'center' } )
        param.args.(varargin{ii} ) = varargin{ii+1};
    end % switch varargin
end % for ii

end % function setparam