Model

class gamspy.Model(container: Container, name: str | None = None, problem: Problem | str = Problem.LP, equations: list[Equation] = [], sense: Sense | str | None = None, objective: Variable | Expression | None = None, matches: dict | None = None, limited_variables: Iterable[Variable] | None = None)

Bases: object

Represents a list of equations to be solved.

Parameters:

containerContainer

Container of the model.

namestr, optional

Name of the model. Name is autogenerated by default.

equationsstr | Iterable

List of Equation objects or str. all as a string represents all the equations specified before the creation of this model.

problemProblem or str, optional

‘LP’, ‘NLP’, ‘QCP’, ‘DNLP’, ‘MIP’, ‘RMIP’, ‘MINLP’, ‘RMINLP’, ‘MIQCP’, ‘RMIQCP’, ‘MCP’, ‘CNS’, ‘MPEC’, ‘RMPEC’, ‘EMP’, or ‘MPSGE’, by default Problem.LP.

senseSense, optional

“MIN”, “MAX”, or “FEASIBILITY”.

objectiveVariable | Expression, optional

Objective variable to minimize or maximize or objective itself.

limited_variablesIterable, optional

Allows limiting the domain of variables used in a model.

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> v = gp.Variable(m, "v")
>>> e = gp.Equation(m, "e", definition= v == 5)
>>> my_model = gp.Model(m, "my_model", "LP", [e])

Attributes:

infeasibility_tolerance

This option sets the tolerance for marking an equation infeasible in the equation listing.

Methods

compute_infeasibilities()	Computes infeasabilities for all equations of the model
freeze(modifiables[, freeze_options])	Freezes all symbols except modifiable symbols.
getDeclaration()	Declaration of the Model in GAMS
getStatement()	Statement of the Model declaration
interrupt()	Sends interrupt signal to the running job.
solve([solver, options, solver_options, ...])	Generates the gams string, writes it to a file and runs it
unfreeze()	Unfreezes all symbols

compute_infeasibilities() → dict[str, pd.DataFrame]

Computes infeasabilities for all equations of the model

Returns:

dict[str, pd.DataFrame]

Dictionary of infeasibilities where equation names are keys and infeasibilities are values

property infeasibility_tolerance: float | None

This option sets the tolerance for marking an equation infeasible in the equation listing. By default, 1.0e-13.

Returns:

float | None

interrupt() → None

Sends interrupt signal to the running job.

Raises:

ValidationError

If the job is not initialized

freeze(modifiables: list[Parameter | ImplicitParameter], freeze_options: dict | None = None) → None

Freezes all symbols except modifiable symbols.

Parameters:

modifiablesList[Parameter | ImplicitParameter]

freeze_optionsdict, optional

unfreeze() → None

Unfreezes all symbols

solve(solver: str | None = None, options: Options | None = None, solver_options: dict | None = None, model_instance_options: ModelInstanceOptions | dict | None = None, output: io.TextIOWrapper | None = None, backend: Literal['local', 'engine', 'neos'] = 'local', client: EngineClient | NeosClient | None = None, create_log_file: bool = False) → pd.DataFrame | None

Generates the gams string, writes it to a file and runs it

Parameters:

solverstr, optional

Solver name

optionsOptions, optional

GAMS options

solver_optionsdict, optional

Solver options

model_instance_optionsoptional

Model instance options

outputTextIOWrapper, optional

Output redirection target

backendstr, optional

Backend to run on

clientEngineClient, NeosClient, optional

EngineClient to communicate with GAMS Engine or NEOS Client to communicate with NEOS Server

create_log_filebool

Allows creating a log file

Returns:

DataFrame, optional

Raises:

ValidationError

In case engine_config is not provided for engine backend or neos_client is not provided for neos backend.

ValueError

In case problem is not in possible problem types

ValueError

In case sense is different than “MIN” or “MAX”

getDeclaration() → str

Declaration of the Model in GAMS

Returns:

str

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> v = gp.Variable(m, "v")
>>> e = gp.Equation(m, "e", definition= v == 5)
>>> my_model = gp.Model(m, "my_model", "LP", [e])
>>> my_model.getDeclaration()
'Model my_model / e /;'

getStatement() → str

Statement of the Model declaration

Returns:

str

class gamspy.ModelStatus(value)

Bases: Enum

An enumeration for model status types

OptimalGlobal = 1

OptimalLocal = 2

Unbounded = 3

InfeasibleGlobal = 4

InfeasibleLocal = 5

InfeasibleIntermed = 6

Feasible = 7

Integer = 8

NonIntegerIntermed = 9

IntegerInfeasible = 10

LicenseError = 11

ErrorUnknown = 12

ErrorNoSolution = 13

NoSolutionReturned = 14

SolvedUnique = 15

Solved = 16

SolvedSingular = 17

UnboundedNoSolution = 18

InfeasibleNoSolution = 19

class gamspy.SolveStatus(value)

Bases: Enum

An enumeration for solve status types

NormalCompletion = 1

IterationInterrupt = 2

ResourceInterrupt = 3

TerminatedBySolver = 4

EvaluationInterrupt = 5

CapabilityError = 6

LicenseError = 7

UserInterrupt = 8

SetupError = 9

SolverError = 10

InternalError = 11

Skipped = 12

SystemError = 13