add fold method

Author: dlegland

src/@Image/Image.m

@@ -90,6 +90,7 @@
     img = zeros(varargin)
     img = false(varargin)
     img = true(varargin)
+    img = fold(varargin)
 
     img = read(fileName, varargin)
     img = readSeries(fileName, varargin)

src/@Image/fold.m

@@ -0,0 +1,45 @@
+function img = fold(array, dims, varargin)
+% Create a new vector image by folding row elements in an array.
+%
+%   IMG = fold(ARRAY, DIMS)
+%   Transforms the N-by-P numeric array into a vector image with P channels
+%   and spatial dimensions given by DIMS. The products of DIMS must equal
+%   the number of rows in the array (N).
+%
+%   Example
+%     % Read color image, and convert to N-by-P data array
+%     img = Image.read('peppers.png');
+%     data = double(unfold(img));
+%     % Performs basic clustering
+%     km = kmeans(data, 6);
+%     % Convert result to imaeg using the 'fold' method
+%     img2 = Image.fold(km+1, size(img), 'type', 'label', 'Name', 'km3 labels');
+%     figure; show(label2rgb(img2, 'jet'));
+%
+%   See also
+%     unfold
+%
+ 
+% ------
+% Author: David Legland
+% e-mail: david.legland@inrae.fr
+% INRAE - BIA Research Unit - BIBS Platform (Nantes)
+% Created: 2020-10-19,    using Matlab 9.8.0.1323502 (R2020a)
+% Copyright 2020 INRAE.
+
+nr = size(array, 1);
+nc = size(array, 2);
+
+if prod(dims) ~= nr
+    error('The number of elements of output image must match the row nomber of array');
+end
+
+data = zeros([dims nc], 'like', array);
+
+subs = {':', ':', 1};
+for i = 1:nc
+    subs{end} = i;
+    data(subs{:}) = reshape(array(:,i), dims);
+end
+
+img = Image('Data', data, 'vector', nc > 1, varargin{:});

src/@Image/kmeans.m

@@ -23,7 +23,7 @@
 %     figure; show(rgb);
 %
 %   See also
-%     label2rgb
+%     label2rgb, fold
 %
 
 % ------

src/@Image/unfold.m

@@ -17,7 +17,7 @@
 %           196608           3
 %
 %   See also
-%     Table, kmeans
+%     Table, fold, kmeans
 %
 
 % ------