Generating Exaustive Parameter Combinations

Question

Florian Rössing 2022-11-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1866668-generating-exaustive-parameter-combinations

评论： Bruno Luong 2022-12-3

采纳的回答： Bruno Luong

在 MATLAB Online 中打开

Hi Everyone.

I want to create many Simulink.SimulationInput Objekts to simulate with many parameters.

To achieve this I am looking for a way to create exhaustive combinations of parameters.

I have not yet decided but thought, that structs might be usefull here. So far the Idea looks like this:

%function simIn = createSimIn(ModelName,Parameters)
%    ParameterNames = fieldnames(Parameters);
%    simIn(1:length(Parameters)) = Simulink.SimulationInput(ModelName);
%    for i = 1:length(Parameters)
%        for ii = 1:length(ParameterNames)
%            simIn(i) = simIn(i).setVariable(ParameterNames(ii),Paramters(i).(ParameterNames(ii)),'Workspace',simIn(i).ModelName);
%        end
%    end
%end

To get this running I would need a way to create a struct with and exhaustive combination of the parameters.

Lets say I have parameters:

a = 1:5;
b= 0:0.1:0.4;
Example = struct('a',num2cell(a),'b',num2cell(b))
Example = 1×5 struct array with fields:
    a
    b

I would want to create a struct that contains an exhaustive combinations, for a known number of parameters and equal lengths i can do:

Example = struct('a',num2cell(sort(repmat(a,1,length(b)))), ...
                 'b',num2cell(repmat(b,1,length(a),1)))
Example = 1×25 struct array with fields:
    a
    b

But I would want to do it for an arbitrary number of parameters and arbitrary multiplicities for the parameters. Is there an easier way to do this?

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Jan 2022-11-29

What about using meshgrid or loops?

Florian Rössing 2022-11-30

Loops are my fallback option, but they are ugly, so i hoped there might be a nicer way to doing this.

Meshgrids i never heard of before, but I just looked it up, looks like you can only use that for 2 and 3D Data.

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Answer 1

Bruno Luong 2022-11-30

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1866668-generating-exaustive-parameter-combinations#answer_1116033

编辑：Bruno Luong 2022-11-30

在 MATLAB Online 中打开

I start with a scalar structure s rather than the structure array, since paramereters might have different lengths

s=struct('a', 1:3, ...
    'b', 1:4, ...
    'c', 1:5)
s = struct with fields:
    a: [1 2 3]
    b: [1 2 3 4]
    c: [1 2 3 4 5]
c = struct2cell(s);
n = length(c);
[c{:}] = ndgrid(c{:});
A = reshape(cat(n+1,c{:}),[],n);
sarg = [fieldnames(s)'; num2cell(num2cell(A),1)];
Sexpand = struct(sarg{:})'
Sexpand = 1×60 struct array with fields:
    a
    b
    c

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Bruno Luong 2022-12-2

Sorry my code is never intended to work on anything different than numerical data.

Bruno Luong 2022-12-3

在 MATLAB Online 中打开

Here is the fix:

s=struct('a', 1:3, ...
    'b', 1:4, ...
    'c', 1:5, ...
    'str', "Test")
s = struct with fields:
      a: [1 2 3]
      b: [1 2 3 4]
      c: [1 2 3 4 5]
    str: "Test"
c = cellfun(@num2cell,struct2cell(s),'unif',0);
n = length(c);
[c{:}] = ndgrid(c{:});
A = reshape(cat(n+1,c{:}),[],n);
sarg = [fieldnames(s)'; num2cell(A,1)];
Sexpand = struct(sarg{:});
Sexpand(1)
ans = struct with fields:
      a: 1
      b: 1
      c: 1
    str: "Test"
Sexpand(end)
ans = struct with fields:
      a: 3
      b: 4
      c: 5
    str: "Test"