MATLAB: To convert a variable (struct with fields of numeric matrix) to a sliced variable (an array of struct)

MATLABsliced variable

I was doing code refactor to apply parfor to some legacy code. Legacy code creates a big struct variable called 'Boot', with fields of numeric matrix.

I want to convert it to a new sliced variable "BootS" , but if I do the conversion like the attached image, Matlab give me warnings that I should preallocate it.

( iters means number of iterations.)

I tried to preallocate BootS as the code commented out , it fails with runtime errors.

Anyone has good idea to convert it elegantly??

Best Answer

closed

see answer above

Related Solutions

MATLAB: Using struct as a reduction variable in parfor loop

https://www.mathworks.com/help/parallel-computing/reduction-variable.html#bq_ttk5

Basic Rules for Reduction Variables

Required (static): You cannot index or subscript a reduction variable.

The example showing something invalid is a struct field access, so the documentation explicitly rules out using a struct field as a reduction variable.

MATLAB: Struct variable save in parfor loop

I doubt that parfor wil work happily with dynamic fieldnames, because their order of definition is ambiguous (e.g .consider naming them using the mod of your loop counter: parfor cannot predict in which order the fields should be overwritten, which for a normal for loop is unambiguous).

The best solution is to avoid the awkward, ambiguous, anti-pattern dynamic fieldnames, and just use simpler indexing with a non-scalar structure:

N = 3;
S = struct('val',cell(1,N));
parfor k = 1:N
    S(k).val = k*2;
end

Unlike your "perfect" code, this really does keep all of the data that you calculate:

>> S.val
ans =
     2
ans =
     4
ans =
     6

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

Best Answer

Related Solutions

MATLAB: Using struct as a reduction variable in parfor loop

MATLAB: Struct variable save in parfor loop

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