Creating an array of objects in a class

Question

Jeffrey Alido 2017-8-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/354379-creating-an-array-of-objects-in-a-class

编辑： per isakson 2017-9-1

I have two .m files for class tree and class leaf:

classdef Tree
    properties
        leaves = [];
        for i = 1:100
            leaves = [leaves Leaf]
        end
    end
    %
    methods (Static = true)
        function show
            for i = 1:100
                leaves(i).show
            end
        end
    end
end

and

classdef Leaf
    properties
        pos = [rand*200 rand*200]
    end
    methods (Static = true)
        function show
            disp('this is a leaf')
        end
    end
end

I'd like to be able create a Tree object with an array of Leaf objects. How may I do this? I'd also like to make the "show" function work.

Thanks!

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Answer 1

Robert U 2017-8-29

1
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https://ww2.mathworks.cn/matlabcentral/answers/354379-creating-an-array-of-objects-in-a-class#answer_279512

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Hi Jeffrey,

here my solution for your tree with leafs:

Tree.m:

 classdef Tree
    properties
        leaves = [];
    end
    methods
        function obj = Tree(nLeaves)
            obj = obj.CreateLeaves(nLeaves);
        end
        function obj = CreateLeaves(obj,N)
            for ik = 1:N
                if ~isempty(obj.leaves)
                    obj.leaves(end+1) = Leaf();
                else
                    obj.leaves = Leaf();
                end
            end
        end
        function showTree(obj)
            if ~isempty(obj.leaves)
                fprintf('The tree has %d leaves.\n\n',length(obj.leaves));
                for ik = 1:length(obj.leaves)
                    fprintf('Leaf %d:\n',ik);
                    obj.leaves(ik).show;
                end
            else
                fprintf('The tree has no leaves.\n');
            end
        end
    end
 end

Leaf.m:

 classdef Leaf
    properties
        pos = [];
    end
    methods
        function obj = Leaf(~)
            obj = obj.RandomPos;
        end
        function show(obj)
            fprintf('This is a single leaf at (%.2f, %.2f).\n\n',obj.pos(1),obj.pos(2))
        end
    end
    methods (Access = private)
        function obj = RandomPos(obj)
            currSetting = rng;
            rng('shuffle');
            obj.pos = [rand*200 rand*200]; 
            rng(currSetting);
        end
    end
 end