Nested Structure to Flat Cell Vector

Tools to flatten a nested struct into cell

Description

flatNestedStructAccessList.m:
=======================
Create a string list of all possible structure access operators (like 'x.y.z')

flattenNestedStruct.m
===============
Uses flatStructAccessList.m to flatten a nested structure into a column of cells.

NOTE
====
This is NOT a GUI program despite what you see in the screenshots. The screenshot how it was used for my project.

I haven't tested this program much except in my project. Please report any bug to [e-mail].

• MATLAB release: MATLAB 7.5 (R2007b)
• Other Files: flattenNestedStruct.m, ; flatNestedStructAccessList.m

[Duane Hanselman]

This might be useful, but being a 23+ year MATLAB user, I can't figure out what it does from the help text. I am especially troubled by the appearance of the function eval being called within a for loop. Would it make sense to make flatStructAccessList to be a subfunction of flattenStruct? Does this do what the builtin function struct2cell already does? What is meant by saying "No vector (or cell vector) allowed anywhere in the input struct!"?

[Hoi Wong]

Thanks Duane for the useful comments. I actually thought of spending more time on the help file, but I just find it quite difficult to describe what the program does without an example screenshot that has the structure displayed as a tree. I'll post a screen shot in a day or two, and I'd appreciate any help describing what this program does in simple words.

struct2cell() works for one level structures only. Hence if you have a structed formed by

a.b.c.d = 1
a.p.q.r = 2

struct2cell() will still give you cells that contains structs, which is not what I wanted (basically I want to form a table from a nested struct).

Also, in this context, since I want a list of all possible leaf nodes in a nested struct, using anything other than feval will make the program extremely clumsy. Please let me know if anybody has a better idea :)

I intentionally separate flatStructAccessList() from flatStruct() because some people might just want a list (like tree view) without the computational work putting all the contents into a cell vector.

By the way, "No vector (or cell vector)" should be written as "No non-singleton struct branch allowed". For structs, it's possible to have something like:

a{1}.b=1
a{2}.c=3
p(1).q=2
p(2).q=4

In this case, 'a' is a vector of cells which all the elements are structs, and 'p' is a vector which all the elements are structs. I don't know how to describe them in simple words, so please help!

If you found a good way to describe it, send me a email at [e-mail].

[e lee]

I found this very handy, I wanted to do a simple check if a nested structure field existed or not, but it seems overly difficult to do this (exist doesn't work for nested structure fiels, isvar works for one level of nesting, etc.)
I was able to do a strcmp on the output to find if the nested structure field exists.

I would also really like to have a gui (like what is shown) that lets you see and edit the values of the structure easily. I would love to have a "tree grid" where nodes could be collapsed (similar to what you show on the right part of the screen shot, with an additional column for the values. But, maybe I am dreaming.

For handling "non-singleton struct branch" perhaps you can find some hints in the Geodise "xml toolbox", it seems to be able to parse pretty complicated matlab structures into xml.

Regards,
Eric

[Ofek Shilon]

Exactly what i needed, works like charm. thanks!