MATLAB: Abbreviate acces to struct fields

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Hello everyone,

i often need to acces a struct field like

sturcture.firstLevel.secondLevel.thirdLevel = 1

Now my question is: Is there a way to abbreviate this long code? Something like defining a pointer.

For example:

    sThird = pointer(sturcture.firstLevel.secondLevel.thirdLevel)

Whereas from now I could substitute

    sThird

for

    sturcture.firstLevel.secondLevel.thirdLevel

Is there a way to do this, so my code is to long?

Thank you for your time reading this.

Rafael

Best Answer

With structures, no it's not possible. Matlab does not support pointers/reference to variables. The workaround is to define a new variable, use that variable to do whatever you wanted to do, and then reassign that variable back to the structure

sThird = structure.firstLevel.secondLevel.thirdLevel;
%do something with sThird
structure.firstLevel.secondLevel.thirdLevel = sThird;

The only other way would be for the content of that thirdLevel field to be a handle class object that wrap whatever it is you store in there. In my opinion, this would be a waste of time just to offer shorter typing in the editor.

edit: forgot another option, which I also don't think is a good idea, use getfield and setfield:

field = {'firstlevel', 'secondlevel', 'thirdLevel'};
value = getfield(structure, field);
setfield(structure, field, someothervalue);

Related Solutions

MATLAB: Create a nested structure using a variable as field name

This is a job for the getfield and setfield commands:

PathStr = '\levelOne\levelTwo\levelThree';  % Do not shadow the PATH command
Fields  = strsplit(PathStr,'\');   % Ignore initial blank field later
S = [];
S = setfield(S, Fields{2:end}, 1)
V = getfield(S, Fields{2:end})

Internally this calls subsassgn, which can be done directly also. I'd move this into a function, which ignores at least a leading separator automatically:

function S = SetPathField(S, PathStr, Value)
if length(PathStr) >= 1 && PathStr(1) == '\'
  Fields = regexp(PathStr(2:end), '\', 'split');
else
  Fields = regexp(PathStr, '\', 'split');
end
Types    = cell(1, numel(Fields));
Types(:) = {'.'};
S        = subsasgn(S, struct('type', Types, 'subs', Fields), Value);
end

MATLAB: How to delete a field from a struct

Make sure to assign the revised struct back to the original variable. For instance, to remove field "field" from "s", use:

>> s = rmfield(s,field)

For more information, see the below documentation reference:

https://www.mathworks.com/help/matlab/ref/rmfield.html

Best Answer

Related Solutions

MATLAB: Create a nested structure using a variable as field name

MATLAB: How to delete a field from a struct

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