How do I insert a substructure within an existing structure at a specific index

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deathtime 2024-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/2089981-how-do-i-insert-a-substructure-within-an-existing-structure-at-a-specific-index

编辑： Stephen23 2024-3-4

Let's say I have an existing structure:

existingStruct.a.val1 = 1;
existingStruct.a.val2 = 2;
existingStruct.b.val1 = 3;
existingStruct.b.val2 = 4;
existingStruct.c.val1 = 5;
existingStruct.c.val2 = 6;
existingStruct.d.val1 = 7;
existingStruct.d.val2 = 8;

Now I have a substructure:

new.val1 = 9;
new.val2 = 10;

I want to place this substructure within b and c in the existing sturcure. So the new structure looks like this:

existingStruct.a.val1 = 1;
existingStruct.a.val2 = 2;
existingStruct.b.val1 = 3;
existingStruct.b.val2 = 4;
existingStruct.new.val1 = 9;
existingStruct.new.val2 = 10;
existingStruct.c.val1 = 5;
existingStruct.c.val2 = 6;
existingStruct.d.val1 = 7;
existingStruct.d.val2 = 8;

What is the simplest way to do this?

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Answer 1

Stephen23 2024-3-4

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https://ww2.mathworks.cn/matlabcentral/answers/2089981-how-do-i-insert-a-substructure-within-an-existing-structure-at-a-specific-index#answer_1420596

编辑：Stephen23 2024-3-4

在 MATLAB Online 中打开

"What is the simplest way to do this?"

With a structure array this would be easy with some indexing. It would also make accessing the data easier.

But because you are using a scalar structure with lots of fields (and most likely forced meta-data into the fieldnames) you will have to do this a longer way e.g. one of these:

STRUCT2CELL, insert, CELL2STRUCT.
ORDERFIELDS:

existingStruct.a.val1 = 1;
existingStruct.a.val2 = 2;
existingStruct.b.val1 = 3;
existingStruct.b.val2 = 4;
existingStruct.c.val1 = 5;
existingStruct.c.val2 = 6;
existingStruct.d.val1 = 7;
existingStruct.d.val2 = 8;
new.val1 = 9;
new.val2 = 10;
existingStruct.new = new;
existingStruct = orderfields(existingStruct,{'a','b','new','c','d'})
existingStruct = struct with fields:
      a: [1×1 struct]
      b: [1×1 struct]
    new: [1×1 struct]
      c: [1×1 struct]
      d: [1×1 struct]

You can use FIELDNAMES() to get a cell array of the fieldnames.

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deathtime 2024-3-4

What if I wanted to duplicate the field "b" in the existing structure - just call the duplicated field "new", and have it in the position as before, between "b" and "c".

Stephen23 2024-3-4

编辑：Stephen23 2024-3-4

在 MATLAB Online 中打开

"What if I wanted to duplicate the field "b" in the existing structure - just call the duplicated field "new", and have it in the position as before, between "b" and "c"."

existingStruct.a.val1 = 1;
existingStruct.a.val2 = 2;
existingStruct.b.val1 = 3;
existingStruct.b.val2 = 4;
existingStruct.c.val1 = 5;
existingStruct.c.val2 = 6;
existingStruct.d.val1 = 7;
existingStruct.d.val2 = 8;
existingStruct.new = existingStruct.b;
existingStruct = orderfields(existingStruct,{'a','b','new','c','d'})
existingStruct = struct with fields:
      a: [1×1 struct]
      b: [1×1 struct]
    new: [1×1 struct]
      c: [1×1 struct]
      d: [1×1 struct]