How to convert all of a structures fields into strings that represent the complete names.

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John Petersen
John Petersen on 28 Apr 2022
Edited: John Petersen on 28 Apr 2022
I have a structure of variable numbers of fields. I want to display them on a GUI so that they can be changed by a user. So I want to display the field names just as you would see them in matlab.
For example, let's say the structure is
Offset = struct('X',0,'Y',0,'Z',0);
Rot = struct('Roll',0,'Pitch',0,'Yaw',0);
IMU = struct('Offset',Offset,'Rot',Rot);
EKFerrors = struct('MeasTimeout',1,'MaxBound',3);
EKF = struct('IMU',IMU,'Errors',EKFerrors,'InitMode',2);
So the list of elements of the structure are shown below
EKF.IMU.Offset.X
EKF.IMU.Offset.Y
EKF.IMU.Offset.Z
EKF.IMU.Rot.Roll
EKF.IMU.Rot.Pitch
EKF.IMU.Rot.Yaw
EKF.Errors.MeasTimeout
EKF.Errors.MaxBound
EKF.InitMode
I would like each of these in an array of strings or cells of strings that I can display on the GUI just as they are shown here (not their value, their name), but I would have an edit box so a user could enter in values. I just need the struct converted to these strings.

Accepted Answer

Stephen23
Stephen23 on 28 Apr 2022
Edited: Stephen23 on 28 Apr 2022
The only general solution is to use a recursive function. Here is code which works for scalar structures, although you could extend it to include indexing into non-scalar structures.
Offset = struct('X',0,'Y',0,'Z',0);
Rot = struct('Roll',0,'Pitch',0,'Yaw',0);
IMU = struct('Offset',Offset,'Rot',Rot);
EKFerrors = struct('MeasTimeout',1,'MaxBound',3);
EKF = struct('IMU',IMU,'Errors',EKFerrors,'InitMode',2);
Z = myfun(EKF)
Z = 9×1 cell array
{'EKF.IMU.Offset.X' } {'EKF.IMU.Offset.Y' } {'EKF.IMU.Offset.Z' } {'EKF.IMU.Rot.Roll' } {'EKF.IMU.Rot.Pitch' } {'EKF.IMU.Rot.Yaw' } {'EKF.Errors.MeasTimeout'} {'EKF.Errors.MaxBound' } {'EKF.InitMode' }
function C = myfun(S)
assert(isstruct(S),'Input <S> must be a structure.')
assert(isscalar(S),'Input <S> must be scalar.')
C = {};
recfun(S,inputname(1))
%
function recfun(A,N)
F = fieldnames(A);
for k = 1:numel(F)
T = sprintf('%s.%s',N,F{k});
B = A.(F{k});
if isstruct(B)
assert(isscalar(B),'Structure <%s> must be scalar.',T)
recfun(B,T)
else
C{end+1,1} = T;
end
end
end
end
  1 Comment
John Petersen
John Petersen on 28 Apr 2022
Perfect! And thanks for teaching me how to do recursive functions. I thought it might require it, but I wasn't sure how to keep the output building on itself.

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More Answers (1)

Image Analyst
Image Analyst on 28 Apr 2022
Use fieldnames():
Offset = struct('X',0,'Y',0,'Z',0);
Rot = struct('Roll',0,'Pitch',0,'Yaw',0);
IMU = struct('Offset',Offset,'Rot',Rot);
EKFerrors = struct('MeasTimeout',1,'MaxBound',3);
EKF = struct('IMU',IMU,'Errors',EKFerrors,'InitMode',2);
OffsetFields = fieldnames(Offset)
OffsetFields = 3×1 cell array
{'X'} {'Y'} {'Z'}
RotFields = fieldnames(Rot)
RotFields = 3×1 cell array
{'Roll' } {'Pitch'} {'Yaw' }
IMUFields = fieldnames(IMU)
IMUFields = 2×1 cell array
{'Offset'} {'Rot' }
EKFerrorsFields = fieldnames(EKFerrors)
EKFerrorsFields = 2×1 cell array
{'MeasTimeout'} {'MaxBound' }
EKFFields = fieldnames(EKF)
EKFFields = 3×1 cell array
{'IMU' } {'Errors' } {'InitMode'}

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