Matlab arrayfun with array of elements that are [1x4 struct] - arrays

Question

I have a array, 'MY_STRUCTURES_Array', with single row and N columns. Each element is a [1x4 struct]. I want to extract a numeric valued 'thisField' from each structure of each [1x4 struct] element.
The result I am looking for is a 4xN array of the values for each 'thisField' value, where each row in this result corresponds to a colum in the [1x4 struct].
The code I am using is this:
arrayfun(#(x) (x.thisField), MY_STRUCTURES_Array);
Matlab returns the error
Attempt to reference field of non-structure array.
If I put the following in the command line,
MY_STRUCTURES_Array{1}
I get a list of all of the fields of the [1x4 struct].
If I put this in the command line,
MY_STRUCTURES_Array{1}.thisField
I get four answers, like this:
ans =
1
ans =
1
ans =
1
ans =
0
If I look at the size
size(MY_STRUCTURES_Array{1}.thisField)
Matlab says "Error using size", so I see this is not an array. But I'm not sure what it is.
I am not sure how to proceed to get the 4xN array I am looking for.
UPDATE
Output from command MY_STRUCTURES_Array returns a row array of [1x4 struct].
Output from whos MY_STRUCTURES_Array{1} returns nothing
Output from whos MY_STRUCTURES_Array returns:
Name Size Bytes Class Attributes
MY_STRUCTURES_Array 1x103 1371136 cell
Output from whos MY_STRUCTURES_Array{1}.thisField returns nothing
Output from MY_STRUCTURES_Array{1}.thisField was shown in the original post.

Answer 1

The fact that you're accessing MY_STRUCTURES_Array as MY_STRUCTURES_Array{1} indicates that it's a cell array, so I'll answer based on that.
Say we have MY_STRUCTURES_Array as a cell array of struct arrays:
MY_STRUCTURES_Array = {[1x4 struct], [1x4 struct], [1x4 struct]}
It contains N elements (here N = 3). Each element is a struct array with 4 elements and various fields. We want to extract the value of field foo, which contains a single number.
out = zeros(4, N);
for it = 1 : N
out(:, it) = [MY_STRUCTURES_Array{it}.foo];
end
out(i, j) now contains the value of MY_STRUCTURES_Array{j}(i).foo
EDIT:
Using arrayfun():
out = arrayfun(#(x) x.foo, cell2mat(MY_STRUCTURES_Array')')
This converts the cell array of struct arrays into a 2d struct array, then extracts field foo from each element.