PiecewiseLinearFunction

(class from pyomo.contrib.piecewise.piecewise_linear_function)

class pyomo.contrib.piecewise.piecewise_linear_function.PiecewiseLinearFunction(*args, **kwds)[source]

Bases: Block

A piecewise linear function, which may be defined over an index.

Can be specified in one of several ways:

List of points and a nonlinear function to approximate. In this case, the points will be used to derive a triangulation of the part of the domain of interest, and a linear function approximating the given function will be calculated for each of the simplices in the triangulation. In this case, scipy is required (for multivariate functions).
List of simplices and a nonlinear function to approximate. In this case, a linear function approximating the given function will be calculated for each simplex. For multivariate functions, numpy is required.
List of simplices and list of functions that return linear function expressions. These are the desired piecewise functions corresponding to each simplex.
Mapping of function values to points of the domain, allowing for the construction of a piecewise linear function from tabular data.

Parameters:

function – Nonlinear function to approximate: must be callable
function_rule – Function that returns a nonlinear function to approximate for each index in an IndexedPiecewiseLinearFunction
points – List of points in the same dimension as the domain of the function being approximated. Note that if the pieces of the function are specified this way, we require scipy.
simplices – A list of lists of points, where each list specifies the extreme points of a a simplex over which the nonlinear function will be approximated as a linear function.
linear_functions – A list of functions, each of which returns an expression for a linear function of the arguments.
tabular_data – A dictionary mapping values of the nonlinear function to points in the domain
triangulation (optional) – An enum value of type Triangulation specifying how Pyomo should triangulate the function domain, or None. Behavior depends on how this piecewise-linear function is constructed: when constructed using methods (1) or (4) above, valid arguments are the members of Triangulation except Unknown or AssumeValid, and Pyomo will use that method to triangulate the domain and to tag the resulting PWLF. If no argument or None is passed, the default is Triangulation.Delaunay. When constructed using methods (2) or (3) above, valid arguments are only Triangulation.Unknown and Triangulation.AssumeValid. Pyomo will tag the constructed PWLF as specified, trusting the user in the case of AssumeValid. When no argument or None is passed, the default is Triangulation.Unknown

__init__(*args, **kwargs)[source]: Constructor

Methods

`__init__`(args, *kwargs)	Constructor
`activate`()	Set the active attribute to True
`clear`()	Clear the data in this component
`clear_suffix_value`(suffix_or_name[, expand])	Clear the suffix value for this component data
`cname`(args, *kwds)	DEPRECATED.
`construct`([data])	Initialize the block
`deactivate`()	Set the active attribute to False
`dim`()	Return the dimension of the index
`display`([filename, ostream, prefix])	Display values in the block
`get_suffix_value`(suffix_or_name[, default])	Get the suffix value for this component data
`getname`([fully_qualified, name_buffer, ...])	Returns the component name associated with this object.
`id_index_map`()	Return an dictionary id->index for all ComponentData instances.
`index_set`()	Return the index set
`is_component_type`()	Return True if this class is a Pyomo component
`is_constructed`()	Return True if this class has been constructed
`is_expression_type`([expression_system])	Return True if this numeric value is an expression
`is_indexed`()	Return true if this component is indexed
`is_logical_type`()	Return True if this class is a Pyomo Boolean object.
`is_named_expression_type`()	Return True if this numeric value is a named expression
`is_numeric_type`()	Return True if this class is a Pyomo numeric object
`is_parameter_type`()	Return False unless this class is a parameter object
`is_reference`()	Return True if this component is a reference, where "reference" is interpreted as any component that does not own its own data.
`is_variable_type`()	Return False unless this class is a variable object
`items`([sort, ordered])	Return an iterator of (index,data) component data tuples
`iteritems`()	DEPRECATED.
`iterkeys`()	DEPRECATED.
`itervalues`()	DEPRECATED.
`keys`([sort, ordered])	Return an iterator over the component data keys
`model`()	Returns the model associated with this object.
`parent_block`()	Returns the parent of this object.
`parent_component`()	Returns the component associated with this object.
`pprint`([ostream, verbose, prefix])	Print component information
`reconstruct`([data])	REMOVED: reconstruct() was removed in Pyomo 6.0.
`register_private_data_initializer`(initializer)
`root_block`()	Return self.model()
`set_suffix_value`(suffix_or_name, value[, expand])	Set the suffix value for this component data
`set_value`(value)	Set the value of a scalar component.
`to_dense_data`()	TODO
`type`()	DEPRECATED.
`valid_model_component`()	Return True if this can be used as a model component.
`values`([sort, ordered])	Return an iterator of the component data objects

Attributes

`active`	Return the active attribute
`ctype`	Return the class type for this component
`local_name`	Get the component name only within the context of the immediate parent container.
`name`	Get the fully qualified component name.

Member Documentation

activate(): Set the active attribute to True

clear(): Clear the data in this component

clear_suffix_value(suffix_or_name, expand=True): Clear the suffix value for this component data

cname(*args, **kwds): DEPRECATED.

Deprecated since version 5.0: The cname() method has been renamed to getname(). The preferred method of obtaining a component name is to use the .name property, which returns the fully qualified component name. The .local_name property will return the component name only within the context of the immediate parent container.

construct(data=None): Initialize the block

deactivate(): Set the active attribute to False

dim(): Return the dimension of the index

display(filename=None, ostream=None, prefix=''): Display values in the block

get_suffix_value(suffix_or_name, default=None): Get the suffix value for this component data

getname(fully_qualified=False, name_buffer=None, relative_to=None)

Returns the component name associated with this object.

Parameters:

fully_qualified (bool) – Generate full name from nested block names
relative_to (Block) – Generate fully_qualified names relative to the specified block.

id_index_map(): Return an dictionary id->index for all ComponentData instances.

index_set(): Return the index set

is_component_type(): Return True if this class is a Pyomo component

is_constructed(): Return True if this class has been constructed

is_expression_type(expression_system=None): Return True if this numeric value is an expression

is_indexed(): Return true if this component is indexed

is_logical_type()

Return True if this class is a Pyomo Boolean object.

Boolean objects include constants, variables, or logical expressions.

is_named_expression_type(): Return True if this numeric value is a named expression

is_numeric_type(): Return True if this class is a Pyomo numeric object

is_parameter_type(): Return False unless this class is a parameter object

is_reference(): Return True if this component is a reference, where “reference” is interpreted as any component that does not own its own data.

is_variable_type(): Return False unless this class is a variable object

items(sort=<SortComponents.UNSORTED: 0>, ordered=NOTSET)

Return an iterator of (index,data) component data tuples

Parameters:

sort (bool or SortComponents) – Iterate over the declared component items in a specified sorted order. See SortComponents for valid options and descriptions.
ordered (bool) – DEPRECATED: Please use sort=SortComponents.ORDERED_INDICES. If True, then the items are returned in a deterministic order (using the underlying set’s ordered_iter().

iteritems()

DEPRECATED.

Return a list (index,data) tuples from the dictionary

Deprecated since version 6.0: The iteritems method is deprecated. Use dict.items().

iterkeys()

DEPRECATED.

Return a list of keys in the dictionary

Deprecated since version 6.0: The iterkeys method is deprecated. Use dict.keys().

itervalues()

DEPRECATED.

Return a list of the component data objects in the dictionary

Deprecated since version 6.0: The itervalues method is deprecated. Use dict.values().

keys(sort=<SortComponents.UNSORTED: 0>, ordered=NOTSET)

Return an iterator over the component data keys

This method sets the ordering of component data objects within this IndexedComponent container. For consistency, __init__(), values(), and items() all leverage this method to ensure consistent ordering.

Parameters:

sort (bool or SortComponents) – Iterate over the declared component keys in a specified sorted order. See SortComponents for valid options and descriptions.
ordered (bool) – DEPRECATED: Please use sort=SortComponents.ORDERED_INDICES. If True, then the keys are returned in a deterministic order (using the underlying set’s ordered_iter()).

model(): Returns the model associated with this object.

parent_block(): Returns the parent of this object.

parent_component(): Returns the component associated with this object.

pprint(ostream=None, verbose=False, prefix=''): Print component information

reconstruct(data=None)

REMOVED: reconstruct() was removed in Pyomo 6.0.

Re-constructing model components was fragile and did not correctly update instances of the component used in other components or contexts (this was particularly problemmatic for Var, Param, and Set). Users who wish to reproduce the old behavior of reconstruct(), are comfortable manipulating non-public interfaces, and who take the time to verify that the correct thing happens to their model can approximate the old behavior of reconstruct with:

component.clear() component._constructed = False component.construct()

root_block(): Return self.model()

set_suffix_value(suffix_or_name, value, expand=True): Set the suffix value for this component data

set_value(value): Set the value of a scalar component.

to_dense_data(): TODO

type()

DEPRECATED.

Return the class type for this component

Deprecated since version 5.7: Component.type() method has been replaced by the .ctype property.

valid_model_component(): Return True if this can be used as a model component.

values(sort=<SortComponents.UNSORTED: 0>, ordered=NOTSET)

Return an iterator of the component data objects

Parameters:

sort (bool or SortComponents) – Iterate over the declared component values in a specified sorted order. See SortComponents for valid options and descriptions.
ordered (bool) – DEPRECATED: Please use sort=SortComponents.ORDERED_INDICES. If True, then the values are returned in a deterministic order (using the underlying set’s ordered_iter().

property active: Return the active attribute

property ctype: Return the class type for this component

property local_name: Get the component name only within the context of the immediate parent container.

property name: Get the fully qualified component name.