Concatenate name fields in nested structure

Hello, 

I am trying to save value of the data placed in the last fields in nested structure by concatenating string in recursion. The name of the file should string composed of the all preceding fields in structure.

However I am not able to save previous fields.

The code is as follows:

nameDataBase = 'database.mat';
structNest = load([pathFolder, nameDataBase]);
structFields =  myIsField(structNest, 'data');
pathOutputFile = pathFolder;
fileName = ''
function isFieldResult = myIsField (inStruct, fieldName)
% inStruct is the name of the structure or an array of structures to search
% fieldName is the name of the field for which the function searches
B = struct();
display('output folder')
isFieldResult = 0;
f = fieldnames(inStruct(1))
f1 = string(fieldnames(inStruct(1)))
for i=1:1%length(f)
    display("i")
    i
    if(strcmp(f{i},strtrim(fieldName)))
        isFieldResult = 1;
        display('data found - end')
        B.(f{i}) = inStruct(1).(f{i})
        data = getfield(B,'data')
        return;
    elseif isstruct(inStruct(1).(f{i}))
        isFieldResult = myIsField(inStruct(1).(f{i}), fieldName);
        B.(f{i}) = inStruct(1).(f{i})
        if isFieldResult
            display('time found -loop')
            return;
        end
    end
end

[Ganesh]

If you could upload the file 'database.mat' and describe what the output you would like to see is, it would be very helpful.

Answer 1

[Voss]

S = struct( ...
    'A1',1, ...
    'A2',struct('B1',2,'not_data',3,'data',4), ...
    'A3',struct( ...
        'B1',struct('not_data',5), ...
        'B2',struct( ...
            'C1',struct('data',6), ...
            'data',struct( ...
                'D1',struct('data',7)))))

S = struct with fields:
    A1: 1
    A2: [1x1 struct]
    A3: [1x1 struct]

S.A2

ans = struct with fields:
          B1: 2
    not_data: 3
        data: 4

S.A3

ans = struct with fields:
    B1: [1x1 struct]
    B2: [1x1 struct]

S.A3.B1

ans = struct with fields:
    not_data: 5

S.A3.B2

ans = struct with fields:
      C1: [1x1 struct]
    data: [1x1 struct]

S.A3.B2.C1

ans = struct with fields:
    data: 6

S.A3.B2.data

ans = struct with fields:
    D1: [1x1 struct]

S.A3.B2.data.D1

ans = struct with fields:
    data: 7

function [out,data] = get_full_field_names(S,name,str)
out = strings(0);
data = cell(0);
if nargin < 3
    str = "";
end
f = fieldnames(S);
for ii = 1:numel(f)
    if isstruct(S.(f{ii}))
        [new_out,new_data] = get_full_field_names(S.(f{ii}),name,str+f{ii}+".");
        out = [out, new_out];
        data = [data, new_data];
    elseif strcmp(f{ii},name)
        out = [out, str+name];
        data = [data, {S.(f{ii})}];
    end
end
end


[names,data] = get_full_field_names(S,'data')

names = 1x3 string array
    "A2.data"    "A3.B2.C1.data"    "A3.B2.data.D1.data"

data = 1x3 cell array
    {[4]}    {[6]}    {[7]}

[names,data] = get_full_field_names(S,'not_data')

names = 1x2 string array
    "A2.not_data"    "A3.B1.not_data"

data = 1x2 cell array
    {[3]}    {[5]}

[names,data] = get_full_field_names(S,'something_else')

names = 

  0x0 empty string array


data =

  0x0 empty cell array

[Elzbieta]

Voss, Thank you a lot. However each string composed of the structure fields should containing data at its end should be name of the separeted file. I do not join data fields with ech other. For instance:

S1.a1.time-> I do not create a separate file

S1.a1.data -> I create file S1_a1_data

S2.a1.time-> I do not create a separate file

S2.a1.data -> I create file S2_a1_data

[Elzbieta]

How to include only these structure fields having also specified field previously like a1?

[Voss]

You're welcome!

"However each string composed of the structure fields should containing data at its end should be name of the separeted file."

I don't understand the objection. The code returns the "full path" through the nested structure of all terminal (non-structure) fields whose name is the requested name (e.g., 'data'). So if you do

get_full_field_names(S,'data')

it will return those locations corresponding to fields called 'data' (and not 'time' or anything else). It also returns the data (i.e., the value of each field 'data') corresponding to each of those locations. So you could create the files like:

[names,data] = get_full_field_names(S,'data');
for ii = 1:numel(names)
    x = data{ii};
    save(names(ii),'x'); % save variable x to mat file called names(ii)
end

If you want underscores instead of periods in the file names, replace "." with "_" here:

[new_out,new_data] = get_full_field_names(S.(f{ii}),name,str+f{ii}+"_");

% ^ here

If you want the name of the top-level structure (e.g., "S2") to be included in the file names, you can prepend it:

[names,data] = get_full_field_names(S2,'data');

names = "S2"+names;

"How to include only these structure fields having also specified field previously like a1?"

You can filter the results after the fact, as in:

[names,data] = get_full_field_names(S,'data');
idx = contains(names,"a1_"); % or "a1." if using period delimiter
names = names(idx);
data = data(idx);

[Elzbieta]

Thank you for your comments. Voss your solution works great!

[Voss]

You're welcome and thank you!