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How to efficiently preallocate an array of handle objects

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Herbert
Herbert el 30 de Mzo. de 2015
Comentada: broken_arrow el 11 de Mzo. de 2023
Hi, I'm looking a fast and proper method to preallocate an array of objects, where the corresponding class is a handle class.
So far, I came across the following methods. But I'm not sure whether all of them are really preallocating the needed space.
1) Is this really preallocating the needed space?
x=myClass.empty(1e5,0);
2)
x(1:1e5) = myClass( param1, param2 );
3) I think this only work if the constructor accept nargin=0, right?
x(1e5) = myClass( param1, param2 );
4) In the case the class also inherits from matlab.mixin.Copyable
x= repmat( copy( myClass( param1, param2), 1e5,1 );

Respuestas (1)

Disciple of the Forbidden Spell
Disciple of the Forbidden Spell el 19 de Mzo. de 2018
To preallocate the object array, assign the last element of the array first. MATLAB® fills the first to penultimate array elements with default ObjectArray objects.
  2 comentarios
Guillaume
Guillaume el 19 de Mzo. de 2018
This is option #3 in the question. As the OP stated, it only works if the constructor is designed to accept 0 arguments.
Furthermore, the behaviour for handle object is far from ideal. You'll end up with an array of n-1 duplicate handles and a different handle at the end, instead of n different handles, as explained in the doc.
broken_arrow
broken_arrow el 11 de Mzo. de 2023
So which method would be considered best practice in this case?

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