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Checklist

  • Appropriate tests were added
  • Any code changes were done in a way that does not break public API
  • All documentation related to code changes were updated
  • The new code follows the
    contributor guidelines, in particular the SciML Style Guide and
    COLPRAC.
  • Any new documentation only uses public API

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@Vaibhavdixit02
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https://github.com/SciML/Optimization.jl/actions/runs/10977080544/job/30478629355?pr=823 documentation failure seems real, can you take a look?

end
mof = MultiObjectiveOptimizationFunction(multi_obj_func_2)
prob = Optimization.OptimizationProblem(mof, u0; lb = [0.0, 0.0], ub = [2.0, 2.0])
sol = solve(prob_2, opt, NumDimensions=2, FitnessScheme=ParetoFitnessScheme{2}(is_minimizing=true))
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Suggested change
sol = solve(prob_2, opt, NumDimensions=2, FitnessScheme=ParetoFitnessScheme{2}(is_minimizing=true))
sol = solve(prob, opt, NumDimensions=2, FitnessScheme=ParetoFitnessScheme{2}(is_minimizing=true))

return [f1, f2]
end
initial_guess = [1.0, 1.0]
function gradient_multi_objective(x, p=nothing)
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Since this isn't used please remove it

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It is used in the MultiObjectiveOptimizationFunction call below and is passed as the jac arg.

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But Evolutionary doesn't need derivatives right?

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Yeah just checked the testing once again and it is not needed, so will remove it.

npartitions = 100
# reference points (Das and Dennis's method)
weights = gen_ref_dirs(nobjectives, npartitions)
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This function is missing here

@Vaibhavdixit02
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@ParasPuneetSingh please take a look at the review above

@Vaibhavdixit02
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Can you rebase on master there was an incorrect compat there that made the docs environment fail here I have updated it

```

## Multi-objective optimization
The optimizer for Multi-Objective Optimization is `BBO_borg_moea()`. Your objective function should return a tuple of the objective values and you should indicate the fitness scheme to be (typically) Pareto fitness and specify the number of objectives. Otherwise, the use is similar, here is an example:
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Why a tuple? That is not going to scale well.

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Yeah corrected that mistake to vector, the struct uses a vector of objective functions.

end
mof = MultiObjectiveOptimizationFunction(multi_obj_func)
prob = Optimization.OptimizationProblem(mof, u0; lb = [0.0, 0.0], ub = [2.0, 2.0])
sol = solve(prob, opt, NumDimensions=2, FitnessScheme=ParetoFitnessScheme{2}(is_minimizing=true))
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NumDimensions, FitnessScheme, those don't match Julia style.

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Those should be in the opt.

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NumDimensions should be computed from the MultiObjectiveOptimizationFunction, FitnessScheme should be in the opt.

function func(x, p=nothing)::Vector{Float64}
f1 = (1.0 - x[1])^2 + 100.0 * (x[2] - x[1]^2)^2 # Rosenbrock function
f2 = -20.0 * exp(-0.2 * sqrt(0.5 * (x[1]^2 + x[2]^2))) - exp(0.5 * (cos(2π * x[1]) + cos(2π * x[2]))) + exp(1) + 20.0 # Ackley function
return [f1, f2]
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it's an array now? Is there an in-place form?

# In this example, we have no constraints
gx = [0.0] # Inequality constraints (not used)
hx = [0.0] # Equality constraints (not used)
return [f1, f2], gx, hx
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This is now a third API?

function multi_obj_func(x, p)
f1 = (1.0 - x[1])^2 + 100.0 * (x[2] - x[1]^2)^2 # Rosenbrock function
f2 = -20.0 * exp(-0.2 * sqrt(0.5 * (x[1]^2 + x[2]^2))) - exp(0.5 * (cos(2π * x[1]) + cos(2π * x[2]))) + exp(1) + 20.0 # Ackley function
return (f1, f2)
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you didn't actually change it though?

@Vaibhavdixit02
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@ParasPuneetSingh please finish this up.

@ParasPuneetSingh
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@ChrisRackauckas please review this at the earliest.

f2 = -20.0 * exp(-0.2 * sqrt(0.5 * (x[1]^2 + x[2]^2))) - exp(0.5 * (cos(2π * x[1]) + cos(2π * x[2]))) + exp(1) + 20.0 # Ackley function
return (f1, f2)
end
mof = MultiObjectiveOptimizationFunction(multi_obj_func)
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Suggested change
mof = MultiObjectiveOptimizationFunction(multi_obj_func)
mof = MultiObjectiveOptimizationFunction(multi_obj_func, obj_prototype = zeros(2))

Comment on lines 79 to 82
function multi_obj_func(x, p)
f1 = (1.0 - x[1])^2 + 100.0 * (x[2] - x[1]^2)^2 # Rosenbrock function
f2 = -20.0 * exp(-0.2 * sqrt(0.5 * (x[1]^2 + x[2]^2))) - exp(0.5 * (cos(2π * x[1]) + cos(2π * x[2]))) + exp(1) + 20.0 # Ackley function
return (f1, f2)
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Show in-place form too?

@ChrisRackauckas
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This is not ready. There's a few steps here. First of all, we document the OptimizationFunction interface https://github.com/SciML/SciMLBase.jl/blob/master/src/scimlfunctions.jl#L1913-L2030 . Right now, MultiObjectiveOptimizationFunction's interface is not documented. Let's start there.

https://github.com/SciML/SciMLBase.jl/blob/master/src/scimlfunctions.jl#L2063-L2066

Write a similar docstring that describes the interface on MultiObjectiveOptimizationFunction. The closest interface should be the NonlinearLeastSquares, since NonlinearLeastSquares is a multi-objective optimization that just has a canonical coalesce via coalesce(cost,u,p) = norm(cost,2).

So okay, what should this thing be? It should be as follows. You have an out of place form cost = f(u,p) and an in-place form f!(cost,u,p). You'll have to have a required cost_prototype which is the vector to use for the in-place cost. This means that length(cost) is equal to the number of objectives. isinplace should then be counting for in-place when you have 3 values, thus matching the same setup as NonlinearFunction. You then need to describe the argument structures expected for each of the derivative definitions, which is more or less matching that of NonlinearLeastSquares. And there should be an optional coalesce(cost,u,p) = norm(cost,2) which when provided allows the MOO problem to be solved with a scalar optimization problem under the definition of coalesce(f(u,p).

Once you have that down, we merge, and then let's use that defined interface. You'll need to MultiobjectiveOptimizationFunction(f; cost_prototype = zeros(2)) some definitions, and then the functions here should not require the user pass in the dimension, since that can be known from the function definition itself.

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3 participants