#
# 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:
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# 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
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# 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 typing import Literal
from typing import TYPE_CHECKING
from typing import Union
import gams.transfer as gt
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.utils as utils
from gamspy._symbols.symbol import Symbol
if TYPE_CHECKING:
from gamspy._symbols.implicits.implicit_set import ImplicitSet
from gamspy import Set, Container
from gamspy._algebra.expression import Expression
[docs]class Alias(gt.Alias, operable.Operable, Symbol):
"""
Represents an Alias symbol in GAMS.
https://www.gams.com/latest/docs/UG_SetDefinition.html#UG_SetDefinition_TheAliasStatementMultipleNamesForASet
Parameters
----------
container : Container
name : str
alias_with : Set
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, "i")
>>> j = gp.Alias(m, "j", i)
"""
def __new__(cls, container: Container, name: str, alias_with: Set):
if not isinstance(container, gp.Container):
raise TypeError(
"Container must of type `Container` but found"
f" {type(container)}"
)
if not isinstance(name, str):
raise TypeError(f"Name must of type `str` but found {type(name)}")
try:
symobj = container[name]
if isinstance(symobj, cls):
return symobj
else:
raise TypeError(
f"Cannot overwrite symbol `{name}` in container"
" because it is not an Alias object)"
)
except KeyError:
return object.__new__(Alias)
def __init__(self, container: Container, name: str, alias_with: Set):
# enable load on demand
self._is_dirty = False
# check if the name is a reserved word
name = utils._reserved_check(name)
super().__init__(container, name, alias_with)
self._container_check(self.domain)
# allow conditions
self.where = condition.Condition(self)
# add statement
self.container._add_statement(self)
# iterator index
self._current_index = 0
def __len__(self):
if self.records is not None:
return len(self.records.index)
return 0
def __next__(self):
if self._current_index < len(self):
row = self.records.iloc[self._current_index]
self._current_index += 1
return row
self._current_index = 0
raise StopIteration
def __iter__(self):
return self
# Set Attributes
@property
def pos(self):
"""
Element position in the current set, starting with 1.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.pos", None)
@property
def ord(self):
"""
Same as .pos but for ordered sets only.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.ord", None)
@property
def off(self):
"""
Element position in the current set minus 1. So .off = .pos - 1
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.off", None)
@property
def rev(self):
"""
Reverse element position in the current set, so the value for
the last element is 0, the value for the penultimate is 1, etc.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.rev", None)
@property
def uel(self):
"""
Element position in the unique element list.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.uel", None)
@property
def len(self):
"""
Length of the set element name (a count of the number of characters).
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.len", None)
@property
def tlen(self):
"""
Length of the set element text (a count of the number of characters).
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.tlen", None)
@property
def val(self):
"""
If a set element is a number, this attribute gives the value of the number.
For extended range arithmetic symbols, the symbols are reproduced.
If a set element is a string that is not a number, then this attribute is
not defined and trying to use it results in an error.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.val", None)
@property
def tval(self):
"""
If a set element text is a number, this attribute gives the value of the number.
For extended range arithmetic symbols, the symbols are reproduced.
If a set element text is a string that is not a number, then this attribute is
not defined and trying to use it results in an error.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.tval", None)
@property
def first(self):
"""
Returns 1 for the first set element, otherwise 0.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.first", None)
@property
def last(self):
"""
Returns 1 for the last set element, otherwise 0.
Returns
-------
Expression
"""
return expression.Expression(None, f"{self.name}.last", None)
[docs] def lag(
self,
n: Union[int, Symbol, Expression],
type: Literal["linear", "circular"] = "linear",
) -> ImplicitSet:
"""Lag operation shifts the values of a Set or Alias by one to the left
Parameters
----------
n : int | Symbol | Expression
type : 'linear' or 'circular', optional
Returns
-------
ImplicitSet
Raises
------
ValueError
When type is not circular or linear
"""
jump = n if isinstance(n, int) else n.gamsRepr() # type: ignore
if type == "circular":
return implicits.ImplicitSet(self, name=f"{self.name} -- {jump}")
elif type == "linear":
return implicits.ImplicitSet(self, name=f"{self.name} - {jump}")
raise ValueError("Lag type must be linear or circular")
[docs] def lead(
self,
n: Union[int, Symbol, Expression],
type: Literal["linear", "circular"] = "linear",
) -> ImplicitSet:
"""
Lead shifts the values of a Set or Alias by one to the right
Parameters
----------
n : int | Symbol | Expression
type : 'linear' or 'circular', optional
Returns
-------
ImplicitSet
Raises
------
ValueError
When type is not circular or linear
"""
jump = n if isinstance(n, int) else n.gamsRepr() # type: ignore
if type == "circular":
return implicits.ImplicitSet(self, name=f"{self.name} ++ {jump}")
elif type == "linear":
return implicits.ImplicitSet(self, name=f"{self.name} + {jump}")
raise ValueError("Lead type must be linear or circular")
[docs] def sameAs(self, other: Union[Set, Alias]) -> Expression:
return expression.Expression(
"sameAs(", ",".join([self.gamsRepr(), other.gamsRepr()]), ")"
)
[docs] def gamsRepr(self) -> str:
"""
Representation of this Alias in GAMS language.
Returns
-------
str
"""
return self.name
[docs] def getStatement(self) -> str:
"""
Statement of the Alias definition
Returns
-------
str
"""
return f"Alias({self.alias_with.name},{self.name});"
