Is {} used as index array in class?

Hi, While I am studying Matlab object oriented I found this example and I want to confirm it.

I have a constructor:

        function obj = DocPortfolio(name,varargin)
            if nargin > 0
                obj.name = name;
                for k = 1:length(varargin)
                    obj.indAssets{k} = varargin(k);
                    assetValue = obj.indAssets{k}{1}.currentValue;
                    obj.totalValue = obj.totalValue + assetValue;
                end
            end
        end

indAssets is an array property. Is it true that obj.indAssets{k} is a way to index into this array? Cause I have never use {} to index array before. And what is obj.indAssets{k}{1} in next line?

This is the link to the example: http://www.mathworks.com/help/matlab/matlab_oop/a-simple-class-hierarchy.html

Thanks!

Answer 1

[Cedric]

Your question is not related to OOP. Look at the following:

 >> c = {5, {'Hello', 'World'}, struct( 'a', 8, 'b', 9 )} ;
 c = [5]    {1x2 cell}    [1x1 struct]

Here, c is a cell array (an array of cells).

 >> class( c )
 ans = cell

You can index blocks of this cell array using ()-type indexing.

 >> c(1:2)
 ans = [5]    {1x2 cell}

 >> c(1)
 ans = [5]

The latter is the first element of the cell array c, which is a cell in itself.

 >> class( c(1) )
 ans = cell

For extracting the content of this cell, you have to use {}-type indexing.

 >> c{1}
 ans = 5

This time it (the content) is the double 5.

 >> class( c{1} )
 ans = double

Now indexing can be "nested"; c{2} is the content of cell #2 of the cell array c. This content is a cell array in itself, that you can again index with both () and {} whether you want cells or their content.

 >> c{2}
 ans = 'Hello'  'World'

 >> class( c{2}(1) )
 ans = cell

 >> class( c{2}{1} )
 ans = char

Or when the content is a struct..

 >> class( c{3} )
 ans = struct

 >> c{3}.a
 ans = 8

Hope it helps,

Cedric

[Thang Nguyen]

Thanks Cedric for spending time to answer my question. I highly appreciate your help!

[Cedric]

You are most welcome! Please accept the Answer if it answers your question.