How to export sub/nested structures using writestruct?

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Dear all,
Let's say I have structure with 3 sub-strucures such as is also a structure.
I want to export in XML the structures keeping the same tree structure.
I started to write a function:
function export_structure(input_structure)
% 0/ input structure informations
struct_name = inputname(1);
names = fieldnames(input_structure);
nfields = length(names);
% 1/ initialisation to find sub structures
count_substructs= 0;
substruct_names = string([1:nfields]);
% 2/ find the sub structures' names
for k = 1:nfields
if isstruct(input_structure.(names{k})) == 1
count_substructs = count_substructs+1;
substruct_names(k) = names{k};
end
end
% 3/ remove the extra sub structures added by the initialisation
if count_substructs ~= 0
substruct_names = rmfield(substruct_names,string([count_substructs:nfields]));
end
% 4/ export all the structures
for k = 1:count_substructs+1
if isstruct(input_structure.(names{k})) == 1
export_parameters(input_structure.(substruct_names{k}));
else
writestruct(input_structure, ...
strcat(string(datetime),sprintf(...
"--- %s parameters.xml",struct_name)));
end
end
It seems to work when I don't have sub-structures.
However when I have it does not.
Indeed, during my initialisation step, step 1, I create an array of strings of length which is the maximum number of sub-structs in the input.
Then I try to find the sub-structs names, step 2.
But I don't manage to check if the field of a struct is a stuct or not.
Any ideas?
Thanks a lot.
Best,
louis

Accepted Answer

Chris
Chris on 20 Sep 2022
Edited: Chris on 20 Sep 2022
If you want to write to a single output file, writestruct() already supports nested structs containing scalar or vector values.
If you are experiencing issues, it could be that a field contains a value that isn't a scalar or vector, or that the filename is not valid.
If you want a separate file for each struct, or to write a function that allows other kinds of values, the end of our other answer thread might be a good place to start.

More Answers (1)

Chris
Chris on 18 Sep 2022
Edited: Chris on 18 Sep 2022
In step 3, you are trying to do an rmfield operation on a string array (rmfield is for structs only). If you want to remove the strings that don't correspond to a substruct, you could initialize like:
substruct_names = strings(3,1);
and remove the empty strings in step 3 like:
substruct_names(substruct_names = '') = [];
But then the logic in step 4 doesn't quite work yet.
  6 Comments
Chris
Chris on 20 Sep 2022
Edited: Chris on 20 Sep 2022
Or you could accept my other answer, since I work for internet points. :)
We both learned something that others may want to know. I think that makes this page worth keeping around. (You could edit the initial question for clarity, if you wanted).

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