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

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.

Answer 1

[Stephen23]

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

[John Petersen]

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.

Answer 2

[Image Analyst]

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'}