Alias#

class gamspy.Alias(container: Container, name: str | None = None, alias_with: Set | Alias | None = None)[source]#

Bases: Alias, Operable, Symbol, SetMixin

Represents an Alias symbol in GAMS. https://www.gams.com/latest/docs/UG_SetDefinition.html#UG_SetDefinition_TheAliasStatementMultipleNamesForASet

Parameters:

containerContainer: Container of the alias.
namestr, optional: Name of the alias.
alias_withSet: Alias set object.

Attributes:

alias_with: Returns the aliased object
container: Container of the symbol
description: Returns description of symbol
dimension: Returns the dimension of symbol
domain: Returns list of domains given either as string (* for universe set) or as reference to the Set/Alias object
domain_labels: Returns the column headings for the records DataFrame
domain_names: Returns the string version of domain names
domain_type: Returns the state of domain links
first: Returns 1 for the first set element, otherwise 0.
is_singleton: if symbol is a singleton set
last: Returns 1 for the last set element, otherwise 0.
len: Length of the set element name (a count of the number of characters).
modified: Flag that identifies if the symbol has been modified
name: Name of symbol
number_records: Returns the number of symbol records
off: Element position in the current set minus 1.
ord: Same as .pos but for ordered sets only.
pos: Element position in the current set, starting with 1.
records: Returns the main symbol records
rev: Reverse element position in the current set, so the value for the last element is 0, the value for the penultimate is 1, etc.
summary: Returns a dict of only the metadata
tlen: Length of the set element text (a count of the number of characters).
tval: If a set element text is a number, this attribute gives the value of the number.
uel: Element position in the unique element list.
val: If a set element is a number, this attribute gives the value of the number.

Methods

`equals`(other[, check_uels, ...])	Used to compare the symbol to another symbol.
`gamsRepr`()	Representation of this Alias in GAMS language.
`getDeclaration`()	Declaration of the Alias in GAMS
`getSparsity`()	Gets the sparsity of the symbol w.r.t the cardinality
`isValid`([verbose, force])	Checks if the symbol is in a valid format
`lag`(n[, type])	Lag operation shifts the values of a Set or Alias by one to the left
`lead`(n[, type])	Lead shifts the values of a Set or Alias by one to the right
`pivot`([index, columns, fill_value])	Convenience function to pivot records into a new shape (only symbols with > 1D can be pivoted).
`sameAs`(other)	Evaluates to true if this set is identical to the given set or alias, false otherwise.
`setRecords`(records[, uels_on_axes])	main convenience method to set standard pandas.DataFrame formatted records.
`toList`([include_element_text])	Convenience method to return symbol records as a python list

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, "i")
>>> j = gp.Alias(m, "j", i)

property modified#: Flag that identifies if the symbol has been modified

property alias_with: Set#

Returns the aliased object

Returns:

Set: The aliased Set

gamsRepr() → str[source]#

Representation of this Alias in GAMS language.

Returns:

str

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, "i", domain=["*"], records=['i1','i2'])
>>> j = gp.Alias(m, "j", i)
>>> j.gamsRepr()
'j'

property container#: Container of the symbol

property description: str#

Returns description of symbol

Returns:

str: Description of symbol

property dimension: int#

Returns the dimension of symbol

Returns:

int: Dimension of symbol

property domain: List[Set | str]#

Returns list of domains given either as string (* for universe set) or as reference to the Set/Alias object

Returns:

List[Set | str]: A list of domains given either as string (* for universe set) or as reference to the Set/Alias object

property domain_labels: List[str] | None#

Returns the column headings for the records DataFrame

Returns:

Union[List[str], None]: Column headings for the records DataFrame

property domain_names: List[str]#

Returns the string version of domain names

Returns:

List[str]: A list of string version of domain names

property domain_type: str | None#

Returns the state of domain links

Returns:

str: none, relaxed or regular

equals(other: Set | Alias, check_uels: bool = True, check_element_text: bool = True, check_meta_data: bool = True, verbose: bool = False) → bool[source]#

Used to compare the symbol to another symbol.

Parameters:

otherSet or Alias: The other symbol (Set or Alias) to compare with the current alias.
check_uelsbool, optional: If True, check both used and unused UELs and confirm same order, otherwise only check used UELs in data and do not check UEL order.
check_element_textbool, optional: If True, check that all set elements have the same descriptive element text, otherwise skip.
check_meta_databool, optional: If True, check that symbol name and description are the same, otherwise skip.
verbosebool, optional: If True, return an exception from the asserter describing the nature of the difference.

Returns:

bool: True if the two symbols are equal in the specified aspects; False if they are not equal and verbose is False.

Examples

>>> m = gt.Container()
>>> i = gt.Set(m, "i")
>>> j = gt.Alias(m, "j", i)
>>> print(i.equals(j))  # Compare the Set 'i' with the Alias 'j'
True

property first#

Returns 1 for the first set element, otherwise 0.

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"])
>>> attr[i,"is_first"]  =  i.first
>>> attr.records.values.tolist()
[['seattle', 'is_first', 1.0]]

getDeclaration()[source]#

Declaration of the Alias in GAMS

Returns:

str

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, "i", records=['i1','i2'])
>>> j = gp.Alias(m, "j", i)
>>> j.getDeclaration()
'Alias(i,j);'

getSparsity() → float | None[source]#

Gets the sparsity of the symbol w.r.t the cardinality

Returns:

float | None: Sparsity of an alias

isValid(verbose: bool = False, force: bool = False) → bool#

Checks if the symbol is in a valid format

Parameters:

verbosebool, optional: Throw exceptions if verbose=True, by default False
forcebool, optional: Recheck a symbol if force=True, by default False

Returns:

bool: True if a symbol is in valid format, False otherwise (throws exceptions if verbose=True)

property is_singleton: bool#

if symbol is a singleton set

Returns:

bool: True if the alias is singleton; False otherwise

lag(n: 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:

nint | Symbol | Expression
type‘linear’ or ‘circular’, optional

Returns:

ImplicitSet

Raises:

ValueError: When type is not circular or linear

Examples

>>> import gamspy as gp
>>>
>>> m = gp.Container()
>>> t = gp.Set(m, name="t", description="time sequence", records=[f"y-{x}" for x in range(1987, 1992)])
>>> a = gp.Parameter(m, name="a", domain=[t])
>>> b = gp.Parameter(m, name="b", domain=[t])
>>> c = gp.Parameter(m, name="c", domain=[t])
>>> a[t] = 1986 + gp.Ord(t)
>>> b[t] = -1
>>> b[t] = a[t.lag(1, "linear")]
>>> b.records.values.tolist()
[['y-1988', 1987.0], ['y-1989', 1988.0], ['y-1990', 1989.0], ['y-1991', 1990.0]]
>>> c[t] = a[t.lag(1, "circular")]
>>> c.records.values.tolist()
[['y-1987', 1991.0], ['y-1988', 1987.0], ['y-1989', 1988.0], ['y-1990', 1989.0], ['y-1991', 1990.0]]

property last#

Returns 1 for the last set element, otherwise 0.

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"])
>>> attr[i,"is_last"]  =  i.last
>>> attr.records.values.tolist()
[['new-york', 'is_last', 1.0]]

lead(n: int | Symbol | Expression, type: Literal['linear', 'circular'] = 'linear') → ImplicitSet#

Lead shifts the values of a Set or Alias by one to the right

Parameters:

nint | Symbol | Expression
type‘linear’ or ‘circular’, optional

Returns:

ImplicitSet

Raises:

ValueError: When type is not circular or linear

Examples

>>> import gamspy as gp
>>>
>>> m = gp.Container()
>>> t = gp.Set(m, name="t", description="time sequence", records=[f"y-{x}" for x in range(1987, 1992)])
>>> a = gp.Parameter(m, name="a", domain=[t])
>>> c = gp.Parameter(m, name="c", domain=[t])
>>> d = gp.Parameter(m, name="d", domain=[t])
>>> a[t] = 1986 + gp.Ord(t)
>>> c[t] = -1
>>> c[t.lead(2, "linear")] = a[t]
>>> c.records.values.tolist()
[['y-1987', -1.0], ['y-1988', -1.0], ['y-1989', 1987.0], ['y-1990', 1988.0], ['y-1991', 1989.0]]
>>> d[t.lead(2, "circular")] = a[t]
>>> d.records.values.tolist()
[['y-1987', 1990.0], ['y-1988', 1991.0], ['y-1989', 1987.0], ['y-1990', 1988.0], ['y-1991', 1989.0]]

property len#

Length of the set element name (a count of the number of characters).

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set length values")
>>> attr[i,"length"]  =  i.len
>>> attr.records.values.tolist()
[['seattle', 'length', 7.0], ['san-diego', 'length', 9.0], ['new-york', 'length', 8.0]]

property name#: Name of symbol

property number_records: int#

Returns the number of symbol records

Returns:

int: Number of symbol records

property off#

Element position in the current set minus 1. So .off = .pos - 1

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set off values")
>>> attr[i,"off"]  =  i.off
>>> attr.records.values.tolist()
[['san-diego', 'off', 1.0], ['new-york', 'off', 2.0]]

property ord#

Same as .pos but for ordered sets only.

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set order values")
>>> attr[i,"order"]  =  i.ord
>>> attr.records.values.tolist()
[['seattle', 'order', 1.0], ['san-diego', 'order', 2.0], ['new-york', 'order', 3.0]]

Convenience function to pivot records into a new shape (only symbols with > 1D can be pivoted).

Parameters:

indexList[str] | str, optional: If index is None then it is set to dimensions [0..dimension-1]
columnsList[str] | str, optional: If columns is None then it is set to the last dimension.
fill_valueint | float, optional: Missing values in the pivot will take the value provided by fill_value

Returns:

DataFrame: A new DataFrame containing the pivoted data.

Examples

>>> m = gt.Container()
>>> i = gt.Set(m, "i", records=["seattle", "san-diego"])
>>> j = gt.Set(m, "j", records=["new-york", "chicago", "topeka"])
>>> ij = gt.Set(m, "ij", [i,j], records=[("seattle", "chicago"), ("seattle", "topeka"), ("san-diego", "new-york")])
>>> routes = gt.Alias(m, name="routes", alias_with=ij)
>>> print(routes.pivot(fill_value=""))
          chicago topeka new-york
seattle      True   True
san-diego                    True

property pos#

Element position in the current set, starting with 1.

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set position values")
>>> attr[i,"position"]  =  i.pos
>>> attr.records.values.tolist()
[['seattle', 'position', 1.0], ['san-diego', 'position', 2.0], ['new-york', 'position', 3.0]]

property records: DataFrame | None#

Returns the main symbol records

Returns:

DataFrame | None: The main symbol records, None if no records were set

property rev#

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:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set reverse values")
>>> attr[i,"reverse"]  =  i.rev
>>> attr.records.values.tolist()
[['seattle', 'reverse', 2.0], ['san-diego', 'reverse', 1.0]]

sameAs(other: Set | Alias | str) → Expression#

Evaluates to true if this set is identical to the given set or alias, false otherwise.

Parameters:

otherSet | Alias

Returns:

Expression

Examples

>>> import gamspy as gp

>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego"])
>>> j = gp.Set(m, name="j", records=["new-york", "seattle"])
>>> attr = gp.Parameter(m, "attr", domain = [i, j])
>>> attr[i,j]  =  i.sameAs(j)
>>> attr.records.values.tolist()
[['seattle', 'seattle', 1.0]]

setRecords(records: Any, uels_on_axes: bool = False) → None[source]#

main convenience method to set standard pandas.DataFrame formatted records. If uels_on_axes=True setRecords will assume that all domain information is contained in the axes of the pandas object – data will be flattened (if necessary).

Parameters:

recordsAny
uels_on_axesbool, optional

property summary: dict#

Returns a dict of only the metadata

Returns:

dict: Outputs a dict of only the metadata

property tlen#

Length of the set element text (a count of the number of characters).

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=[("seattle", "Wisconsin"), ("san-diego", ""), ("new-york", " ")], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set element text length values")
>>> attr[i,"text_length"]  =  i.tlen
>>> attr.records.values.tolist()
[['seattle', 'text_length', 9.0], ['new-york', 'text_length', 1.0]]

toList(include_element_text: bool = False) → list[source]#

Convenience method to return symbol records as a python list

Parameters:

include_element_textbool, optional: If True, include the element text as tuples (record, element text). If False, return a list of records only.

Returns:

list: A list containing the records of the symbol.

Examples

>>> m = gt.Container()
>>> i = gt.Set(m, "i", records=["new-york", "chicago", "topeka"])
>>> j = gt.Alias(m, "j", i)
>>> print(j.toList())
['new-york', 'chicago', 'topeka']

property tval#

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:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=[("seattle", "12"), ("san-diego", ""), ("new-york", "-13.4")], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set text values")
>>> attr[i,"text_value"]  =  i.tval
>>> attr.records.values.tolist()
[['seattle', 'text_value', 12.0], ['new-york', 'text_value', -13.4]]

property uel#

Element position in the unique element list.

Returns:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["seattle", "san-diego", "new-york"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set uel_pos values")
>>> attr[i,"uel_position"]  =  i.uel
>>> attr.records.values.tolist()
[['seattle', 'uel_position', 1.0], ['san-diego', 'uel_position', 2.0], ['new-york', 'uel_position', 3.0]]

property val#

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:

ImplicitSet

Examples

>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, name="i", records=["12", "20", "-13.4"], description="canning plants")
>>> attr = gp.Parameter(m, "attr", domain = [i, "*"], description = "Set val values")
>>> attr[i,"value"]  =  i.val
>>> attr.records.values.tolist()
[['12', 'value', 12.0], ['20', 'value', 20.0], ['-13.4', 'value', -13.4]]