from __future__ import annotations
import io
import logging
import os
import uuid
from collections.abc import Iterable
from enum import Enum
from typing import TYPE_CHECKING
from gams.core.gmd import gmdCloseLicenseSession
import gamspy as gp
import gamspy._algebra.expression as expression
import gamspy._algebra.operation as operation
import gamspy._symbols.implicits as implicits
import gamspy._validation as validation
import gamspy.utils as utils
from gamspy._backend.backend import backend_factory
from gamspy._convert import GamsConverter, LatexConverter
from gamspy._model_instance import ModelInstance
from gamspy.exceptions import GamspyException, ValidationError
if TYPE_CHECKING:
from typing import Iterable, Literal
import pandas as pd
from gamspy import Container, Equation, Parameter, Variable
from gamspy._algebra.expression import Expression
from gamspy._algebra.operation import Operation
from gamspy._backend.engine import EngineClient
from gamspy._backend.neos import NeosClient
from gamspy._options import ModelInstanceOptions, Options
from gamspy._symbols.implicits import ImplicitParameter
IS_MIRO_INIT = os.getenv("MIRO", False)
logger = logging.getLogger("MODEL")
logger.setLevel(logging.INFO)
stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.INFO)
formatter = logging.Formatter("[%(name)s - %(levelname)s] %(message)s")
stream_handler.setFormatter(formatter)
logger.addHandler(stream_handler)
[docs]
class Problem(Enum):
"""An enumeration for problem all problem types"""
LP = "LP"
NLP = "NLP"
QCP = "QCP"
DNLP = "DNLP"
MIP = "MIP"
RMIP = "RMIP"
MINLP = "MINLP"
RMINLP = "RMINLP"
MIQCP = "MIQCP"
RMIQCP = "RMIQCP"
MCP = "MCP"
CNS = "CNS"
MPEC = "MPEC"
RMPEC = "RMPEC"
EMP = "EMP"
MPSGE = "MPSGE"
@classmethod
def values(cls):
"""Convenience function to return all values of enum"""
return list(cls._value2member_map_.keys())
def __str__(self) -> str:
return self.value
[docs]
class Sense(Enum):
"""An enumeration for sense types"""
MIN = "MIN"
MAX = "MAX"
FEASIBILITY = "FEASIBILITY"
@classmethod
def values(cls):
"""Convenience function to return all values of enum"""
return list(cls._value2member_map_.keys())
def __str__(self) -> str:
return self.value
[docs]
class ModelStatus(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
[docs]
class SolveStatus(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
INTERRUPT_STATUS = [
SolveStatus.IterationInterrupt,
SolveStatus.ResourceInterrupt,
SolveStatus.EvaluationInterrupt,
SolveStatus.UserInterrupt,
SolveStatus.TerminatedBySolver,
]
ERROR_STATUS = {
SolveStatus.CapabilityError: "The solver does not have the capability required by the model.",
SolveStatus.LicenseError: "The solver cannot find the appropriate license key needed to use a specific subsolver.",
SolveStatus.SetupError: "The solver encountered a fatal failure during problem set-up time.",
SolveStatus.SolverError: "The solver encountered a fatal error.",
SolveStatus.InternalError: "The solver encountered an internal fatal error.",
SolveStatus.SystemError: "This indicates a completely unknown or unexpected error condition.",
}
# GAMS name -> GAMSPy name
ATTRIBUTE_MAP = {
"domUsd": "num_domain_violations",
"etAlg": "algorithm_time",
"etSolve": "total_solve_time",
"etSolver": "total_solver_time",
"iterUsd": "num_iterations",
"marginals": "marginals",
"maxInfes": "max_infeasibility",
"meanInfes": "mean_infeasibility",
"modelStat": "status",
"nodUsd": "num_nodes_used",
"numDepnd": "num_dependencies",
"numDVar": "num_discrete_variables",
"numEqu": "num_equations",
"numInfes": "num_infeasibilities",
"numNLIns": "num_nonlinear_insts",
"numNLNZ": "num_nonlinear_zeros",
"numNOpt": "num_nonoptimalities",
"numNZ": "num_nonzeros",
"numRedef": "num_mcp_redefinitions",
"numVar": "num_variables",
"numVarProj": "num_bound_projections",
"objEst": "objective_estimation",
"objVal": "objective_value",
"procUsed": "used_model_type",
"resGen": "model_generation_time",
"resUsd": "solve_model_time",
"solveStat": "solve_status",
"sumInfes": "sum_infeasibilities",
"sysVer": "solver_version",
}
[docs]
class Model:
"""
Represents a list of equations to be solved.
Parameters
----------
container : Container
Container of the model.
name : str, optional
Name of the model. Name is autogenerated by default.
equations : Iterable[Equation]
Iterable of Equation objects.
problem : Problem or str, optional
'LP', 'NLP', 'QCP', 'DNLP', 'MIP', 'RMIP', 'MINLP', 'RMINLP', 'MIQCP', 'RMIQCP', 'MCP', 'CNS', 'MPEC', 'RMPEC', 'EMP', or 'MPSGE',
by default Problem.LP.
sense : Sense, optional
"MIN", "MAX", or "FEASIBILITY".
objective : Variable | Expression, optional
Objective variable to minimize or maximize or objective itself.
matches : dict[Equation, Variable]
Equation - Variable matches for MCP models.
limited_variables : Iterable, 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])
"""
# Prefix for auto-generated symbols
_generate_prefix = "autogenerated_"
def __init__(
self,
container: Container,
name: str | None = None,
problem: Problem | str = Problem.LP,
equations: Iterable[Equation] = [],
sense: Sense | str | None = None,
objective: Variable | Expression | None = None,
matches: dict[Equation, Variable] | None = None,
limited_variables: Iterable[Variable] | None = None,
):
self._auto_id = str(uuid.uuid4()).replace("-", "_")
if name is not None:
name = validation.validate_name(name)
self.name = validation.validate_model_name(name)
else:
self.name = self._auto_id
self.container = container
self._matches = matches
self.problem, self.sense = validation.validate_model(
equations, problem, sense
)
self.equations = list(equations)
self._objective_variable = self._set_objective_variable(objective)
self._limited_variables = limited_variables
if not self.equations and not self._matches:
raise ValidationError("Model requires at least one equation.")
self.container._add_statement(self)
# allow freezing
self._is_frozen = False
# Attributes
self.num_domain_violations = None
self.algorithm_time = None
self.total_solve_time = None
self.total_solver_time = None
self.num_iterations = None
self.marginals = None
self.max_infeasibility = None
self.mean_infeasibility = None
self.status: ModelStatus | None = None
self.num_nodes_used = None
self.num_dependencies = None
self.num_discrete_variables = None
self.num_infeasibilities = None
self.num_nonlinear_insts = None
self.num_nonlinear_zeros = None
self.num_nonoptimalities = None
self.num_nonzeros = None
self.num_mcp_redefinitions = None
self.num_variables = None
self.num_bound_projections = None
self.objective_estimation = None
self.objective_value = None
self.used_model_type = None
self.model_generation_time = None
self.solve_model_time = None
self.sum_infeasibilities = None
self.solve_status: SolveStatus | None = None
self.solver_version = None
self._infeasibility_tolerance: float | None = None
self.container._synch_with_gams()
def __repr__(self) -> str:
return f"<Model `{self.name}` ({hex(id(self))})>"
def __str__(self) -> str:
return (
f"Model {self.name}:\n Problem Type: {self.problem}\n Sense:"
f" {self.sense}\n Equations: {self.equations}"
)
def _generate_obj_var_and_equation(self) -> tuple[Variable, Equation]:
variable = gp.Variable._constructor_bypass(
self.container,
f"{self.name}_objective_variable",
domain=[],
)
equation = gp.Equation._constructor_bypass(
self.container,
f"{self.name}_objective",
domain=[],
)
return variable, equation
def _set_objective_variable(
self,
assignment: None | Variable | Operation | Expression = None,
) -> Variable | None:
"""
Returns objective variable. If the assignment is an Expression
or an Operation (Sum, Product etc.), it automatically generates
an objective variable and a equation.
Returns
-------
Variable | None
Raises
------
TypeError
In case assignment is not a Variable, Expression or an Operation.
"""
if assignment is not None and not isinstance(
assignment,
(gp.Variable, expression.Expression, operation.Operation),
):
raise TypeError(
"Objective must be a Variable or an Expression but"
f" {type(assignment)} given"
)
if self.sense == gp.Sense.FEASIBILITY:
if assignment is not None:
raise ValidationError(
"Cannot set an objective when the sense is FEASIBILITY!"
)
if self.problem in [gp.Problem.CNS, gp.Problem.MCP]:
raise ValidationError(
"Problem type cannot be CNS or MCP when the sense is"
" FEASIBILITY"
)
variable, equation = self._generate_obj_var_and_equation()
statement = expression.Expression(
implicits.ImplicitEquation(
equation,
name=equation.name,
type=equation.type,
domain=[],
),
"..",
variable == 0,
)
self.container._add_statement(statement)
equation._definition = statement
equation.modified = False
variable.modified = False
self.equations.append(equation)
return variable
if isinstance(
assignment, (expression.Expression, operation.Operation)
):
variable, equation = self._generate_obj_var_and_equation()
# Sum((i,j),c[i,j]*x[i,j])->Sum((i,j),c[i,j]*x[i,j]) =e= var
assignment = assignment == variable
# equation .. Sum((i,j),c[i,j]*x[i,j]) =e= var
statement = expression.Expression(
implicits.ImplicitEquation(
equation,
name=equation.name,
type=equation.type,
domain=[],
),
"..",
assignment,
)
self.container._add_statement(statement)
equation._definition = statement
equation.modified = False
variable.modified = False
self.equations.append(equation)
return variable
return assignment
def _generate_solve_string(self) -> str:
solve_string = f"solve {self.name} using {self.problem}"
if self.sense:
if self.sense == gp.Sense.FEASIBILITY:
# Set sense as min or max for feasibility
self.sense = gp.Sense.MIN
solve_string += f" {self.sense}"
if self._objective_variable is not None:
solve_string += f" {self._objective_variable.gamsRepr()}"
return solve_string + ";"
def _append_solve_string(self) -> None:
solve_string = self._generate_solve_string()
self.container._add_statement(solve_string + "\n")
def _create_model_attributes(self) -> None:
self.container._add_statement("$offListing")
for attr_name in ATTRIBUTE_MAP:
symbol_name = f"{self._generate_prefix}{attr_name}_{self._auto_id}"
_ = gp.Parameter._constructor_bypass(self.container, symbol_name)
self.container._add_statement(
f"{symbol_name} = {self.name}.{attr_name};"
)
self.container._add_statement("$onListing")
def _update_model_attributes(self) -> None:
container = self.container._temp_container
gdx_handle = utils._open_gdx_file(
self.container.system_directory, self.container._gdx_out
)
for gams_attr, python_attr in ATTRIBUTE_MAP.items():
symbol_name = f"{self._generate_prefix}{gams_attr}_{self._auto_id}"
data = utils._get_scalar_data(
container._gams2np, gdx_handle, symbol_name
)
if python_attr == "status":
setattr(self, python_attr, ModelStatus(data))
elif python_attr == "solve_status":
status = SolveStatus(data)
setattr(self, python_attr, status)
if status in INTERRUPT_STATUS:
logger.warn(
f"The solve was interrupted! Solve status: {status.name}. "
"For further information, see https://www.gams.com/latest/docs/UG_GAMSOutput.html#UG_GAMSOutput_SolverStatus."
)
elif status in ERROR_STATUS:
raise GamspyException(
f"Solve status: {status.name}. {ERROR_STATUS[status]}",
status.value,
)
else:
setattr(self, python_attr, data)
utils._close_gdx_handle(gdx_handle)
self.container._temp_container.data = {}
[docs]
def compute_infeasibilities(self) -> 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
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["i1", "i2"])
>>> j = gp.Set(m, name="j", records=["j1", "j2", "j3"])
>>> a = gp.Parameter(m, name="a", domain=i, records=[("i1", 350), ("i2", 600)])
>>> b = gp.Parameter(m, name="b", domain=j, records=[("j1", 400), ("j2", 450), ("j3", 420)])
>>> x = gp.Variable(m, name="x", domain=[i,j], type="Positive")
>>> s = gp.Equation(m, name="s", domain=i)
>>> d = gp.Equation(m, name="d", domain=j)
>>> s[i] = gp.Sum(j, x[i, j]) <= a[i]
>>> d[j] = gp.Sum(i, x[i, j]) >= b[j]
>>> my_model = gp.Model(m, name="my_model", equations=m.getEquations(), problem="LP", sense="min", objective=gp.Sum((i, j), x[i, j]))
>>> summary = my_model.solve()
>>> infeasibilities = my_model.compute_infeasibilities()
>>> infeasibilities["s"].infeasibility.item()
320.0
"""
infeas_dict = {}
for equation in self.equations:
if equation.records is None:
continue
infeas_rows = utils._calculate_infeasibilities(equation)
infeas_dict[equation.name] = infeas_rows
return infeas_dict
@property
def infeasibility_tolerance(self) -> float | None:
"""
This option sets the tolerance for marking an equation infeasible in
the equation listing. By default, 1.0e-13.
Returns
-------
float | None
"""
return self._infeasibility_tolerance
@infeasibility_tolerance.setter
def infeasibility_tolerance(self, value: float):
self.container._add_statement(f"{self.name}.tolInfRep = {value};")
self._infeasibility_tolerance = value
[docs]
def interrupt(self) -> None:
"""
Sends interrupt signal to the running job.
Raises
------
ValidationError
If the job is not initialized
"""
self.container._stop_socket()
[docs]
def freeze(
self,
modifiables: list[Parameter | ImplicitParameter],
options: Options | None = None,
) -> None:
"""
Freezes all symbols except modifiable symbols.
Parameters
----------
modifiables : List[Parameter | ImplicitParameter]
freeze_options : dict, optional
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, name="a", records=10)
>>> x = gp.Variable(m, name="x")
>>> e = gp.Equation(m, name="e", definition= x <= a)
>>> my_model = gp.Model(m, name="my_model", equations=m.getEquations(), problem="LP", sense="max", objective=x)
>>> solved = my_model.solve()
>>> float(x.toValue())
10.0
>>> my_model.freeze(modifiables=[a])
>>> a.setRecords(35)
>>> solved = my_model.solve()
>>> float(x.toValue())
35.0
"""
self._is_frozen = True
self.instance = ModelInstance(
self.container, self, modifiables, options
)
[docs]
def unfreeze(self) -> None:
"""Unfreezes the model"""
self._is_frozen = False
gmdCloseLicenseSession(self.instance.instance.sync_db._gmd)
[docs]
def solve(
self,
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,
) -> pd.DataFrame | None:
"""
Solves the model with given options.
Parameters
----------
solver : str, optional
Solver name
options : Options, optional
GAMS options
solver_options : dict, optional
Solver options
model_instance_options : optional
Model instance options
output : TextIOWrapper, optional
Output redirection target
backend : str, optional
Backend to run on
client : EngineClient, NeosClient, optional
EngineClient to communicate with GAMS Engine or NEOS Client to communicate with NEOS Server
Returns
-------
DataFrame, optional
Summary of the solve
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"
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], "max", v)
>>> solved = my_model.solve()
"""
validation.validate_solver_args(
self.container.system_directory,
solver,
self.problem,
options,
output,
)
validation.validate_equations(self)
if options is None:
options = (
self.container._options
if self.container._options
else gp.Options()
)
options._set_solver_options(
working_directory=self.container.working_directory,
solver=solver,
problem=self.problem,
solver_options=solver_options,
)
if self._is_frozen:
self.instance.solve(solver, model_instance_options, output)
return None
self._append_solve_string()
self._create_model_attributes()
runner = backend_factory(
self.container,
options,
output,
backend,
client,
self,
)
summary = runner.run()
if IS_MIRO_INIT:
self.container._write_default_gdx_miro()
return summary
[docs]
def getDeclaration(self) -> 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 /;'
"""
equations = []
for equation in self.equations:
if self._matches:
if equation not in self._matches:
equations.append(equation.name)
else:
equations.append(equation.name)
equations_str = ",".join(equations)
if self._matches:
matches_str = ",".join(
[
f"{equation.name}.{variable.name}"
for equation, variable in self._matches.items()
]
)
equations_str = (
",".join([equations_str, matches_str])
if equations
else matches_str
)
if self._limited_variables:
limited_variables_str = ",".join(
[variable.gamsRepr() for variable in self._limited_variables]
)
equations_str += "," + limited_variables_str
model_str = f"Model {self.name}"
if equations_str != "":
model_str += f" / {equations_str} /"
model_str += ";"
return model_str
[docs]
def toGams(self, path: str) -> None:
"""
Generates GAMS model under path/<model_name>.gms
Parameters
----------
path : str
Path to the directory which will contain the GAMS model.
"""
converter = GamsConverter(self, path)
converter.convert()
[docs]
def toLatex(self, path: str, generate_pdf: bool = False) -> None:
"""
Generates a latex file that contains the model definition under path/<model_name>.gms
Parameters
----------
path : str
Path to the directory which will contain the .tex file.
"""
converter = LatexConverter(self, path)
converter.convert()
if generate_pdf:
converter.to_pdf()
