Renaming Field Names of a Struct

I have a struct array and I want to create a new one out of it.

I fetch the old name through

fieldnames

and I will only have to add 'AA_'

Example:

old Fieldname: Angle

new Fieldname: AA_Angle

Heres an example:

for ii = 1:dim2(1)
    fName2 = (fieldnames(tmp.(fName)));
    check_struct = isstruct(tmp.(fName).(fName2{ii}));
    if check_struct == 1
        dim3 = size(fieldnames(tmp.(fName).(fName2{ii})));
        for iii = 1:dim3(1)
            fName3 = (fieldnames(tmp.(fName).(fName2{ii})));
            if isequal(fName3{iii},'Name')
                value = getfield(tmp,fName,fName2{ii},fName3{iii});
                novalue = isempty(value);
                if novalue == 1
                    newfile.(fName2{ii}).(fName3{iii}) = fName2{ii}; %% Here the newfile is created and fName2 schould already be with 'AA_....'
                end
            end
        end
    end
end

Any help is appreciated.

Answer 1

[Voss]

If you want to rename the fields of a struct array, you can do so like this:

S = struct('field_1',{1 2},'field_2',{3 4})

S = 1×2 struct array with fields:
    field_1
    field_2

str = 'AA_';
f = fieldnames(S);
f_new = strcat(str,f);
for jj = 1:numel(S)
    for ii = 1:numel(f)
        S(jj).(f_new{ii}) = S(jj).(f{ii});
    end
end
S = rmfield(S,f)

S = 1×2 struct array with fields:
    AA_field_1
    AA_field_2

However, it looks like (maybe?) you want to not only rename the fields of a struct but also rename the fields of any struct that is a field of that struct and so on and so forth ad infinitum. If that's the case you can do so with a recursive function.

S = struct( ...
    'field_1',9, ...
    'field_2',{{1 2}}, ...
    'field_3',struct( ...
        'sub_field_1',[11 12 13], ...
        'sub_field_2',{14 15}));

S_new = prepend_field_names(S,'AA_');

S, S_new

S = struct with fields:
    field_1: 9
    field_2: {[1]  [2]}
    field_3: [1×2 struct]

S_new = struct with fields:
    AA_field_1: 9
    AA_field_2: {[1]  [2]}
    AA_field_3: [1×2 struct]

S.field_3, S_new.AA_field_3

ans = 1×2 struct array with fields:
    sub_field_1
    sub_field_2

ans = 1×2 struct array with fields:
    AA_sub_field_1
    AA_sub_field_2

S.field_3(1), S_new.AA_field_3(1)

ans = struct with fields:
    sub_field_1: [11 12 13]
    sub_field_2: 14

ans = struct with fields:
    AA_sub_field_1: [11 12 13]
    AA_sub_field_2: 14

S.field_3(2), S_new.AA_field_3(2)

ans = struct with fields:
    sub_field_1: [11 12 13]
    sub_field_2: 15

ans = struct with fields:
    AA_sub_field_1: [11 12 13]
    AA_sub_field_2: 15

function S = prepend_field_names(S,str,do_recurse)
f = fieldnames(S);
f_new = strcat(str,f);
for jj = 1:numel(S)
    for ii = 1:numel(f)
        S(jj).(f_new{ii}) = S(jj).(f{ii});
        if (nargin < 3 || do_recurse) && isstruct(S(jj).(f_new{ii}))
            S(jj).(f_new{ii}) = prepend_field_names(S(jj).(f_new{ii}),str,true);
        end
    end
end
S = rmfield(S,f);
end