pyomo.common.enums

This module provides standard enum.Enum definitions used in Pyomo, along with additional utilities for working with custom Enums

Utilities:

ExtendedEnumType(cls, bases, classdict, **kwds)

Metaclass for creating an enum.Enum that extends another Enum

Standard Enums:

ObjectiveSense(value)

Flag indicating if an objective is minimizing (1) or maximizing (-1).

class pyomo.common.enums.ExtendedEnumType(cls, bases, classdict, **kwds)

Metaclass for creating an enum.Enum that extends another Enum

In general, enum.Enum classes are not extensible: that is, they are frozen when defined and cannot be the base class of another Enum. This Metaclass provides a workaround for creating a new Enum that extends an existing enum. Members in the base Enum are all present as members on the extended enum.

Example

class ObjectiveSense(enum.IntEnum):
    minimize = 1
    maximize = -1

class ProblemSense(enum.IntEnum, metaclass=ExtendedEnumType):
    __base_enum__ = ObjectiveSense

    unknown = 0

>>> list(ProblemSense)
[<ProblemSense.unknown: 0>, <ObjectiveSense.minimize: 1>, <ObjectiveSense.maximize: -1>]
>>> ProblemSense.unknown
<ProblemSense.unknown: 0>
>>> ProblemSense.maximize
<ObjectiveSense.maximize: -1>
>>> ProblemSense(0)
<ProblemSense.unknown: 0>
>>> ProblemSense(1)
<ObjectiveSense.minimize: 1>
>>> ProblemSense('unknown')
<ProblemSense.unknown: 0>
>>> ProblemSense('maximize')
<ObjectiveSense.maximize: -1>
>>> hasattr(ProblemSense, 'minimize')
True
>>> ProblemSense.minimize is ObjectiveSense.minimize
True
>>> ProblemSense.minimize in ProblemSense
True

enum pyomo.common.enums.ObjectiveSense(value)

Flag indicating if an objective is minimizing (1) or maximizing (-1).

While the numeric values are arbitrary, there are parts of Pyomo that rely on this particular choice of value. These values are also consistent with some solvers (notably Gurobi).

Member Type:

int

Valid values are as follows:

minimize = <ObjectiveSense.minimize: 1>

maximize = <ObjectiveSense.maximize: -1>