How to check that all entries in a cell array have the same size?

Question

I have a cell array C that whose elements are n-dimensional numeric arrays. For example:

C = {[111 121 131; 211 221 231], ...
     [112 122 132; 212 222 232], ...
     [113 123 133; 213 223 233], ...
     [114 124 134; 214 224 234]};

I'm looking for a convenient way to test that they all the nd-arrays in C have the same shape (as reported by the size function).

The criterion for equality here is not entirely trivial. Depending on the situation one may want to regard a shape of [2 3 4] different from or equal to a shape of, say, [1 2 3 4] or [2 1 3 1 4].

For my immediate purposes I want to treat [2 3 4] as different from [1 2 3 4], etc.

(BTW: order always matters; e.g., [2 3 4] is never equal to [4 3 2], say.)

I tried several things (such as, getting the length of unique(C)), but they all fail... (After almost two years of use, my MATLAB instincts remain close to null.)

Answer 1

Test the size of each cell of C against the size of one cell, for example the first. For testing equality of sizes you need isequal (== won't do because the sizes of the sizes may be different).

all(cellfun(@(e) isequal(size(C{1}), size(e)) , C(2:end)))

If you want to consider a size [2 3 4] equal to [1 2 3 4] etc, just add squeeze:

size1 = size(squeeze(C{1}));
all(cellfun(@(e) isequal(size1, squeeze(size(e))) , C(2:end)))