How do I find all entries in an object array with a certain property

Hi all, this is my first time attempting an object orientated program in Matlab so please bear with me. I have created an object array that for each object in the array has the properties 'Position' and 'Value'. Position saves the position within the array and Value will be either 0 or 1. I would like to be able to find the position of all entries with a 1 as the value. In a normal array I would have used the 'find' command. I have tried using 'findobj' but this results in an error saying I cannot use the method findobj on a class handle. Is there another way I can do this? My code atm is

classdef ObjectArray
    properties
        Value
        Position
        Timer
        NbH1
        NbH2
    end
    methods
        function Cell = ObjectArray(M)
            if nargin ~= 0
                m = size(M,1);
                n = size(M,2);
                Cell(m,n) = ObjectArray;
                for i = 1:m
                    for j = 1:n
                        Cell(i,j).Value = M(i,j);
                        Cell(i,j).Position=[i,j];
                    end
                end
            end
        end
    end
end

Thanks for the help, Carla

Answer 1

[Benjamin Kraus]

There are a variety of ways you can do this. The most straightforward is to use arrayfun:

arr = ObjectArray(rand(10)>0.5);
ind = arrayfun(@(o) o.Value == 1, arr);
pos = vertcat(arr(ind).Position);

[Benjamin Kraus]

Another option is to overload find for your class, and internally call arrayfun (or any other internal implementation you want):

classdef ObjectArray
    ...
    methods
        function ind = find(objarr)
            ind = arrayfun(@(o) o.Value == 1, objarr);
        end
    end
end

Answer 2

[per isakson]

Another approach

>> cc = ClassC( 12 );
>> [cc.a]
ans =
    17    17    17    17    17    17    17    17    17    17    17    17
>> [cc([4,7,11]).a] = deal(1);
>> [cc.a]
ans =
    17    17    17     1    17    17     1    17    17    17     1    17
    

This was a matlabish way to create a sample object array. Now find() finds the ones this way

>> find([cc.a]==1)
ans =
     4     7    11
>> 

where

classdef    ClassC < handle
    properties
        a   double = 17;
    end
    methods
        function  this = ClassC( n )
            if nargin >= 1
                this( 1, n ) = ClassC(); 
            end
        end
    end
end