gemseo / formulations

# idf module¶

The Individual Discipline Feasible (IDF) formulation.

class gemseo.formulations.idf.IDF(disciplines, objective_name, design_space, maximize_objective=False, normalize_constraints=True, n_processes=1, use_threading=True, start_at_equilibrium=False, grammar_type='JSONGrammar')[source]

The Individual Discipline Feasible (IDF) formulation.

This formulation draws an optimization architecture where the coupling variables of strongly coupled disciplines is made consistent by adding equality constraints on the coupling variables at top level, the optimization problem with respect to the local, global design variables and coupling variables is made at the top level.

The disciplinary analysis is made at each optimization iteration while the multidisciplinary analysis is made at the optimum.

Parameters
• disciplines (Sequence[gemseo.core.discipline.MDODiscipline]) – The disciplines.

• objective_name (str) – The name of the objective function. If a sequence is passed, a vector objective function is created.

• design_space (gemseo.algos.design_space.DesignSpace) – The design space.

• maximize_objective (bool) –

If True, the objective function is maximized.

By default it is set to False.

• normalize_constraints (bool) –

If True, the outputs of the coupling consistency constraints are scaled.

By default it is set to True.

• n_processes (int) –

The maximum simultaneous number of threads, if use_threading is True, or processes otherwise, used to parallelize the execution.

By default it is set to 1.

Whether to use threads instead of processes to parallelize the execution; multiprocessing will copy (serialize) all the disciplines, while threading will share all the memory. This is important to note if you want to execute the same discipline multiple times, you shall use multiprocessing.

By default it is set to True.

• start_at_equilibrium (bool) –

If True, an MDA is used to initialize the coupling variables.

By default it is set to False.

• grammar_type (str) –

The type of the input and output grammars, either MDODiscipline.JSON_GRAMMAR_TYPE or MDODiscipline.SIMPLE_GRAMMAR_TYPE.

By default it is set to JSONGrammar.

A user constraint is a design constraint in addition to the formulation specific constraints such as the targets (a.k.a. consistency constraints) in IDF.

The strategy of repartition of constraints is defined in the formulation class.

Parameters
• output_name (str) – The name of the output to be used as a constraint. For instance, if g_1 is given and constraint_type=”eq”, g_1=0 will be added as a constraint to the optimizer.

• constraint_type (str) –

The type of constraint, either “eq” for equality constraint or “ineq” for inequality constraint.

By default it is set to eq.

• constraint_name (str | None) –

The name of the constraint to be stored, If None, the name is generated from the output name.

By default it is set to None.

• value (float | None) –

The value of activation of the constraint. If None, the value is equal to 0.

By default it is set to None.

• positive (bool) –

If True, the inequality constraint is positive.

By default it is set to False.

Return type

None

Add an observable to the optimization problem.

The repartition strategy of the observable is defined in the formulation class.

Parameters
• output_names (str | Sequence[str]) – The name(s) of the output(s) to observe.

• observable_name (str | None) –

The name of the observable.

By default it is set to None.

• discipline (MDODiscipline | None) –

The discipline computing the observed outputs. If None, the discipline is detected from inner disciplines.

By default it is set to None.

Return type

None

classmethod get_default_sub_options_values(**options)

Get the default values of the sub-options of the formulation.

When some options of the formulation depend on higher level options, the default values of these sub-options may be obtained here, mainly for use in the API.

Parameters

**options (str) – The options required to deduce the sub-options grammar.

Returns

Either None or the sub-options default values.

Return type

dict

get_expected_dataflow()[source]

Get the expected data exchange sequence.

This method is used for the XDSM representation and can be overloaded by subclasses.

Returns

The expected sequence of data exchange where the i-th item is described by the starting discipline, the ending discipline and the coupling variables.

Return type
get_expected_workflow()[source]

Get the expected sequence of execution of the disciplines.

This method is used for the XDSM representation and can be overloaded by subclasses.

For instance:

• [A, B] denotes the execution of A, then the execution of B

• (A, B) denotes the concurrent execution of A and B

• [A, (B, C), D] denotes the execution of A, then the concurrent execution of B and C, then the execution of D.

Returns

A sequence of elements which are either an ExecutionSequence or a tuple of ExecutionSequence for concurrent execution.

Return type
get_optim_variables_names()

Get the optimization unknown names to be provided to the optimizer.

This is different from the design variable names provided by the user, since it depends on the formulation, and can include target values for coupling for instance in IDF.

Returns

The optimization variable names.

Return type

list[str]

get_sub_disciplines()

Accessor to the sub-disciplines.

This method lists the sub scenarios’ disciplines.

Returns

The sub-disciplines.

Return type
classmethod get_sub_options_grammar(**options)

Get the sub-options grammar.

When some options of the formulation depend on higher level options, the schema of the sub-options may be obtained here, mainly for use in the API.

Parameters

**options (str) – The options required to deduce the sub-options grammar.

Returns

Either None or the sub-options grammar.

Return type

gemseo.core.grammars.json_grammar.JSONGrammar

get_sub_scenarios()

List the disciplines that are actually scenarios.

Returns

The scenarios.

Return type
get_top_level_disc()[source]

Return the disciplines which inputs are required to run the scenario.

A formulation seeks to evaluate objective function and constraints from inputs. It structures the optimization problem into multiple levels of disciplines. The disciplines directly depending on these inputs are called top level disciplines.

By default, this method returns all disciplines. This method can be overloaded by subclasses.

Returns

The top level disciplines.

Return type

Mask a vector from a subset of names, with respect to a set of names.

This method eventually swaps the order of the values if the order of the data names is inconsistent between these sets.

Parameters
• masking_data_names (Iterable[str]) – The names of the kept data.

• x_vect – The vector to mask.

• all_data_names (Iterable[str] | None) –

The set of all names. If None, use the design variables stored in the design space.

By default it is set to None.

Returns

The masked version of the input vector.

Raises
• IndexError – when the sizes of variables are inconsistent.

• ValueError – when the names of variables are inconsistent.

Return type

ndarray

get_x_names_of_disc(discipline)

Get the design variables names of a given discipline.

Parameters

discipline (gemseo.core.discipline.MDODiscipline) – The discipline.

Returns

The names of the design variables.

Return type

list[str]

Mask a vector from a subset of names, with respect to a set of names.

This method eventually swaps the order of the values if the order of the data names is inconsistent between these sets.

Parameters
• masking_data_names (Iterable[str]) – The names of the kept data.

• x_vect (ndarray) – The vector to mask.

• all_data_names (Iterable[str] | None) –

The set of all names. If None, use the design variables stored in the design space.

By default it is set to None.

Returns

The masked version of the input vector.

Raises

IndexError – when the sizes of variables are inconsistent.

Return type

ndarray

Unmask a vector from a subset of names, with respect to a set of names.

This method eventually swaps the order of the values if the order of the data names is inconsistent between these sets.

Parameters
• masking_data_names (Iterable[str]) – The names of the kept data.

• all_data_names (Iterable[str] | None) –

The set of all names. If None, use the design variables stored in the design space.

By default it is set to None.

• x_full (ndarray) –

The default values for the full vector. If None, use the zero vector.

By default it is set to None.

Returns

The vector related to the input mask.

Raises

IndexError – when the sizes of variables are inconsistent.

Return type

ndarray

NAME: ClassVar[str] = 'MDOFormulation'

The name of the MDO formulation.

property design_space: gemseo.algos.design_space.DesignSpace

The design space on which the formulation is applied.

disciplines: Sequence[MDODiscipline]

The disciplines of the MDO process.

opt_problem: OptimizationProblem

The optimization problem generated by the formulation from the disciplines.