how to rename fields in struc and adding new field name

Hello everyone

I have a stuct to work wit and i wonted to rename the field name (XX) by 'Area (km2)' and also i wanted to add new filed column between YY and ZZ as shown below.

wish you best

Answer 1

[Walter Roberson]

struct fieldnames must be valid MATLAB identifiers, so spaces and brackets are not permitted.

The characters are permitted in the names of Variables in table() objects.

To add a new field at a particular location, the easiest way is to add the new field and then to use orderfields() to change the order.

[TESFALEM ALDADA]

Thank you Walter,

But the idea was to add new field, i confused how to add it.

best

[Walter Roberson]

foo = struct('a', 1, 'b', 2, 'd', 4);
foo.c = 3

foo = struct with fields:
    a: 1
    b: 2
    d: 4
    c: 3

%new field has been added but it is out of place

newfoo = orderfields(foo, {'d', 'c', 'b', 'a'})

newfoo = struct with fields:
    d: 4
    c: 3
    b: 2
    a: 1

%and now it is in very specific place

[TESFALEM ALDADA]

Okey it works fine thank you so much!!

Answer 2

[Jan]

Adding a field at the end is trivial:

porositiy.newField = [];

Adding a field at a specific location is a bad idea, because the order of fields is not really fixed. But it works:

function S = AddFieldAfter(S, AfterField, NewField, NewData)
SField = fieldnames(S);
SData  = struct2cell(S);
nS     = numel(S);
sizeS  = size(S);

index = find(strcmp(SField, AfterField));
if ~isempty(index)
    SField = cat(1, SField(1:index), {NewField}, SField(index + 1:end));
    
    if ~isequal(size(NewData), sizeS)
       NewDataC    = cell([1, nS]);
       NewDataC(:) = {NewData};
    end
    
    SData = cat(1, SData(1:index, 1:nS), NewDataC, SData(index + 1:end, 1:nS));
    S     = reshape(cell2struct(SData, SField), sizeS);
else  % Field not found, append at the end:
    S.(NewField) = NewData;
end
end