MATLAB: How to concatenate or merge two structures

concatenatejoin;MATLABmergestructures

I would like to merge two structures into a new structure containing all the fields of the two original structures. How can I do this in MATLAB?

Best Answer

There is no direct ability in MATLAB that can be used to concatenate structures.

The attached file mergeStructs.m shows a number of methods that can be used to merge structures in MATLAB.

There are also online submissions on the MATLAB Central User Community that you can use. One such submission is :

http://www.mathworks.com/matlabcentral/fileexchange/7842

Note that MathWorks does not guarantee or warrant the use or content of these submissions. Any questions, issues, or complaints should be directed to the contributing author.

Related Solutions

MATLAB: How to conbine the array inside the structure

struct1=struct('f1',num2cell(1:10))
struct2=struct('f2',num2cell(1:5))
new_struct=struct('new_f',num2cell([struct1.f1 struct2.f2 ]))

MATLAB: Partial overwrite of data in a structure

"when I am restructuring the data it always a hassle to put every data holder variable to a proper place" If it's a hassle, then your storage structure is not optimal. You may be better off revising the way you store your data rather than constantly finding workarounds.

To answer your question, this should do what you want:

   function into = mergestruct(into, from)
      %MERGESTRUCT merge all the fields of scalar structure from into scalar structure into
      validateattributes(from, {'struct'}, {'scalar'});
      validateattributes(into, {'struct'}, {'scalar'});
      fns = fieldnames(from);
      for fn = fns.'
         if isstruct(from.(fn{1})) && isfield(into, fn{1})
              %nested structure where the field already exist, merge again
              into.(fn{1}) = mergestruct(into.(fn{1}), from.(fn{1}));
         else
             %non structure field, or nested structure field that does not already exist, simply copy
             into.(fn{1}) = from.(fn{1});
         end
      end
   end

Test:

>> a = struct('a', 1, 'b', 2, 'c', 3, 'd', struct('a', 11, 'b', 12, 'c', struct('a', 111))) 
a =   
  struct with fields:  
    a: 1
    b: 2
    c: 3
    d: [1×1 struct]
>> a.d  
ans =   
  struct with fields:  
    a: 11
    b: 12
    c: [1×1 struct]  
>> a.d.c 
ans =   
  struct with fields:  
    a: 111
>> b = struct('a', -1, 'b', -2, 'd', struct('b', -12, 'c', struct('b', -112)))  
b =   
  struct with fields:  
    a: -1
    b: -2
    d: [1×1 struct]
>> aa = mergestruct(a, b)  
aa =   
  struct with fields:  
    a: -1
    b: -2
    c: 3
    d: [1×1 struct]
>> aa.d  
ans =   
  struct with fields:  
    a: 11
    b: -12
    c: [1×1 struct]
>> aa.d.c  
ans =   
  struct with fields:  
    a: 111
    b: -112

Seems to do what you want.

Best Answer

Related Solutions

MATLAB: How to conbine the array inside the structure

MATLAB: Partial overwrite of data in a structure

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