matlab: Is a field of structure array actually a named cell array?

Question

I've googled topics about difference between cell array and array and had a vision that cell array actually stores pointers to content of elements.

Operator {} is like & in C, right?

When {} is applied to a variable {var_a,var_b}, we get a 1*2 "cell pointers" array to var_a and var_b? Is there a name for the "cell pointer"?

Does structure array take similar memory arrangement?

Take the example in the matlab document:

patient.name = 'John Doe';
patient.billing = 127.00;
patient.test = [79, 75, 73; 180, 178, 177.5; 172, 170, 169];

patient(2).name = 'Ann Lane';
patient(2).billing = 28.50;
patient(2).test = [68, 70, 68; 118, 118, 119; 172, 170, 169];

so the variable patient is like a 2*3 cell array except the field name?

patientcell{2,3}=...

I was wondering the notion below:

The dot operator in structure makes a deference to its content:

patient(1).test;

=> patientcell{1,3}

right?

For more insight, I'd recommend digging into the MEX API to get a feel for how the underlying mxArray works behind the scenes - even numeric arrays really only store pointers to their data (it's how the copy-on-write mechanism works, for one thing) — Notlikethat
– Notlikethat, Commented Mar 8, 2014 at 13:41
I think that to accomplish copy-on-write, numeric arrays just store pointer to the starting element, which is different from cell array. The link in your post is an api list, without detail implementation. It's a pity that mathworks hide these details. — misssprite
– misssprite, Commented Mar 10, 2014 at 8:09

andrelucas · Accepted Answer · 2014-03-08 13:06:42Z

1

Preallocation of cell array in matlab

It is reasonable to assume that a cell array is implemented as a continuous array of pointers, each pointing to the actual content of the cell.

How do i define a structure in Matlab

the structure is simply an array of pointer[s]

answered Mar 8, 2014 at 13:06

andrelucas

6883 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

misssprite Over a year ago

Thanks for confirming my hesitation that structure contains pointers two. Maybe it's a ambiguous itself about the analogy of 2-dimension cell array to structure array. After all, we don't the implementation beneath, and Mathworks don't take this semantic equivalence about the two.

Collectives™ on Stack Overflow

matlab: Is a field of structure array actually a named cell array?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related