MATLAB: How to preallocate an object array

object arraysoop

I am trying to preallocate an object array of a class. Below is the class that I am using in MyobjectArray class 
classdef MyData
    properties
       x = [];  % a column vector of data
    end
        methods
        function obj = MyData(nRows)
            if nRows > 0
                obj.x = zeros(nRows,1);
            end
        end
    end
end
In the code below I am using obj.value = zeros(nArrays,1); to preallocate. What is the correct way to preallocate an object array?
classdef MyobjectArray
    properties
        value = [];  % an array of MyData objects
    end
     methods
        function obj = MyobjectArray(nArrays, nRows)
            if nargin ~= 0
                obj.value = zeros(nArrays,1);
                for i = 1:nArrays
                    obj(i).value = MyData(nRows);
                end
            end
        end
    end
end

Best Answer

Do not initialize value to [] if the property is not going to have type "double" .
If it is going to have type that is one of the built-in types, use empty() to create an empty array of the correct type
https://www.mathworks.com/help/matlab/ref/empty.html#mw_204d42d9-5615-4d04-b95e-4c647e4ca3bd
See also https://www.mathworks.com/help/matlab/matlab_oop/creating-object-arrays.html
If MyData is not going to return double, then do not assign zeros to initialize the property . If MyData(nRows) returns a constant value you would be better with
[obj(1:nArrays).value] = MyData(nRows);
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