If you have the Image Processing Toolbox, you can use PixelValues, which you can get from passing A into regionprops():
% Sample data:
A=[1 2 3 4 29 31 0 0 0 0 0 35 4 5 61 7 0 0 0 1 2 31 91 65];
% Make the measurements. Get all the regions.
regions = regionprops(A>0, A, 'PixelValues')
% Pull them out from the structure into separate variables, if desired.
s1 = regions(1).PixelValues
s2 = regions(2).PixelValues
s3 = regions(3).PixelValues
In the command window:
regions =
3x1 struct array with fields:
PixelValues
s1 =
1 2 3 4 29 31
s2 =
35 4 5 61 7
s3 =
1 2 31 91 65
