Join two different size cells in the same struct

Question

I want to put together 2 cells of different sizes in the same struct. For example:

a = {'one', 'two', 'three'};
b = {'four', 'five', 'six', 'seven'};

struct("setA", a, "setB", b);

Whenever I try to do this, MATLAB throws the following error:

error: struct: dimensions of parameter 2 do not match those of parameter 4

According to the error message the problem is the dimensions of the cells. Furthermore, if I remove one element from cell b the process finishes without errors:

a = {'one', 'two', 'three'};
b = {'four', 'five', 'six'};

struct("setA", a, "setB", b);

Any suggestions?

Answer 1

You need to wrap the cells in another cell to create a scalar struct containing cells in it's fields.

struct('setA', {a}, 'setB', {b})

%   setA: {'one'  'two'  'three'}
%   setB: {'four'  'five'  'six'  'seven'}

By default, struct assumes that a cell means that you want a multi-element struct where each cell element will belong to a different struct. It uses the dimensions of these cells to determine the size of the resulting struct. In your case, the two cell arrays (a and b) are different sizes so it gets confused.

By wrapping each of them inside of another cell, MATLAB will create a scalar struct containing your cell arrays as you expect.