#
# GAMS - General Algebraic Modeling System Python API
#
# Copyright (c) 2023 GAMS Development Corp. <support@gams.com>
# Copyright (c) 2023 GAMS Software GmbH <support@gams.com>
#
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
from __future__ import annotations
from enum import Enum
from typing import Any
from typing import TYPE_CHECKING
import gams.transfer as gt
import pandas as pd
import gamspy as gp
import gamspy._algebra.condition as condition
import gamspy._algebra.expression as expression
import gamspy._algebra.operable as operable
import gamspy._symbols.implicits as implicits
import gamspy._validation as validation
import gamspy.utils as utils
from gamspy._symbols.symbol import Symbol
if TYPE_CHECKING:
from gamspy import Set, Variable, Container
from gamspy._algebra.operation import Operation
from gamspy._algebra.expression import Expression
eq_types = ["=e=", "=l=", "=g="]
non_regular_map = {
"nonbinding": "=n=",
"external": "=x=",
"cone": "=c=",
"boolean": "=b=",
}
[docs]class EquationType(Enum):
REGULAR = "REGULAR"
NONBINDING = "NONBINDING"
EXTERNAL = "EXTERNAL"
CONE = "CONE"
BOOLEAN = "BOOLEAN"
[docs] @classmethod
def values(cls):
return list(cls._value2member_map_.keys())
def __str__(self) -> str:
return self.value
[docs]class Equation(gt.Equation, operable.Operable, Symbol):
"""
Represents an Equation symbol in GAMS.
https://www.gams.com/latest/docs/UG_Equations.html
Parameters
----------
container : Container
name : str
type : str
domain : List[Set | str], optional
definition: Expression, optional
records : Any, optional
domain_forwarding : bool, optional
description : str, optional
uels_on_axes: bool
definition_domain: list, optional
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, "i", records=['i1','i2'])
>>> a = gp.Parameter(m, "a", [i], records=[['i1',1],['i2',2]])
>>> v = gp.Variable(m, "v", domain=[i])
>>> e = gp.Equation(m, "e", domain=[i])
>>> e[i] = a[i] <= v[i]
"""
def __new__(
cls,
container: Container,
name: str,
type: str | EquationType = "regular",
domain: list[Set | str] | None = None,
definition: Variable | Operation | Expression | None = None,
records: Any | None = None,
domain_forwarding: bool = False,
description: str = "",
uels_on_axes: bool = False,
definition_domain: list | None = None,
):
if not isinstance(container, gp.Container):
raise TypeError(
f"Container must of type `Container` but found {container}"
)
if not isinstance(name, str):
raise TypeError(f"Name must of type `str` but found {type(name)}")
try:
symbol = container[name]
if isinstance(symbol, cls):
return symbol
else:
raise TypeError(
f"Cannot overwrite symbol `{name}` in container"
" because it is not an Equation object)"
)
except KeyError:
return object.__new__(cls)
def __init__(
self,
container: Container,
name: str,
type: str | EquationType = "regular",
domain: list[Set | str] | None = None,
definition: Variable | Operation | Expression | None = None,
records: Any | None = None,
domain_forwarding: bool = False,
description: str = "",
uels_on_axes: bool = False,
definition_domain: list | None = None,
):
type = cast_type(type)
self._is_dirty = False
self._is_frozen = False
name = validation.validate_name(name)
super().__init__(
container,
name,
type,
domain,
records,
domain_forwarding,
description,
uels_on_axes,
)
validation.validate_container(self, self.domain)
self.where = condition.Condition(self)
self.container._add_statement(self)
self._definition_domain = definition_domain
self._init_definition(definition)
# create attributes
self._l, self._m, self._lo, self._up, self._s = self._init_attributes()
self._stage = self._create_attr("stage")
self._range = self._create_attr("range")
self._slacklo = self._create_attr("slacklo")
self._slackup = self._create_attr("slackup")
self._slack = self._create_attr("slack")
self._infeas = self._create_attr("infeas")
def __hash__(self):
return id(self)
def __getitem__(self, indices: tuple | str):
domain = (
self.domain
if isinstance(indices, type(...))
else utils._to_list(indices)
)
validation.validate_domain(domain, self)
return implicits.ImplicitEquation(
self, name=self.name, type=self.type, domain=domain # type: ignore # noqa: E501
)
def __setitem__(
self,
indices: tuple | str | implicits.ImplicitSet,
assignment: Expression,
):
domain = (
self.domain
if isinstance(indices, type(...))
else utils._to_list(indices)
)
validation.validate_container(self, domain)
validation.validate_domain(domain, self)
self._set_definition(assignment, domain)
self._is_dirty = True
if not self.container.delayed_execution:
self.container._run()
def __eq__(self, other): # type: ignore
return expression.Expression(self, "=e=", other)
def _init_attributes(self) -> tuple:
level = self._create_attr("l")
marginal = self._create_attr("m")
lower = self._create_attr("lo")
upper = self._create_attr("up")
scale = self._create_attr("scale")
return level, marginal, lower, upper, scale
def _create_attr(self, attr_name):
return implicits.ImplicitParameter(
self,
name=f"{self.name}.{attr_name}",
records=self.records,
domain=self.domain,
)
def _init_definition(
self,
assignment: Variable | Operation | Expression | None = None,
) -> None:
if assignment is None:
self._definition = assignment # type: ignore
return
domain = (
self._definition_domain if self._definition_domain else self.domain
)
self._set_definition(assignment, domain)
def _set_definition(self, assignment, domain):
# In case of an MCP equation without any equality, add the equality
if not any(eq_type in assignment.gamsRepr() for eq_type in eq_types):
assignment = self._adapt_mcp_equation(assignment)
statement = expression.Expression(
implicits.ImplicitEquation(
self,
name=self.name,
type=self.type,
domain=domain,
),
"..",
assignment,
)
self.container._add_statement(statement)
self._definition = statement
def _adapt_mcp_equation(self, assignment: Expression | Operation):
assignment = assignment == 0
if self.type in non_regular_map.keys():
assignment.replace(assignment.data, non_regular_map[self.type])
assignment.data = non_regular_map[self.type]
return assignment
@property
def l(self): # noqa: E741, E743
"""
Level
Returns
-------
ImplicitParameter
"""
return self._l
@property
def m(self):
"""
Marginal
Returns
-------
ImplicitParameter
"""
return self._m
@property
def lo(self):
"""
Lower bound
Returns
-------
ImplicitParameter
"""
return self._lo
@property
def up(self):
"""
Upper bound
Returns
-------
ImplicitParameter
"""
return self._up
@property
def scale(self):
"""
Scale
Returns
-------
ImplicitParameter
"""
return self._s
@property
def stage(self):
"""
Stage
Returns
-------
ImplicitParameter
"""
return self._stage
@property
def range(self):
"""
Range
Returns
-------
ImplicitParameter
"""
return self._range
@property
def slacklo(self):
"""
Slack lower bound
Returns
-------
ImplicitParameter
"""
return self._slacklo
@property
def slackup(self):
"""
Slack upper bound
Returns
-------
ImplicitParameter
"""
return self._slackup
@property
def slack(self):
"""
Slack
Returns
-------
ImplicitParameter
"""
return self._slack
@property
def infeas(self):
"""
Infeasability
Returns
-------
ImplicitParameter
"""
return self._infeas
@property
def records(self):
"""
Records of the Equation
Returns
-------
DataFrame
"""
if not self._is_dirty:
return self._records
self.container._run()
return self._records
@records.setter
def records(self, records):
if records is not None:
if not isinstance(records, pd.DataFrame):
raise TypeError("Symbol 'records' must be type DataFrame")
# set records
self._records = records
self._requires_state_check = True
self.modified = True
self.container._requires_state_check = True
self.container.modified = True
if self._records is not None:
if self.domain_forwarding: # pragma: no cover
self._domainForwarding()
# reset state check flags for all symbols in the container
for symbol in self.container.data.values():
symbol._requires_state_check = True
[docs] def gamsRepr(self) -> str:
"""
Representation of this Equation in GAMS language.
Returns
-------
str
"""
return self.name
[docs] def getStatement(self) -> str:
"""
Statement of the Equation declaration
Returns
-------
str
"""
output = f"Equation {self.name}"
if self.domain:
output += self._get_domain_str()
if self.description:
output += ' "' + self.description + '"'
output += ";"
return output
def cast_type(type: str | EquationType) -> str:
if isinstance(type, str):
if type.upper() not in EquationType.values():
raise ValueError(
"Allowed equation types:"
f" {EquationType.values()} but found {type}."
)
# assign eq by default
if type.upper() == "REGULAR":
type = "EQ"
elif isinstance(type, EquationType):
# assign eq by default
type = "EQ" if EquationType.REGULAR else str(type)
return type
