pywr.nodes.BreakLink

class pywr.nodes.BreakLink(*args, **kwargs)

Compound node used to reduce the number of routes in a model

Parameters

modelpywr.model.Model

namestring

min_flowfloat or pywr.parameters.Parameter

max_flowfloat or pywr.parameters.Parameter

costfloat or pywr.parameters.Parameter

Notes

In a model with form (3, 1, 3), i.e. 3 (A,B,C) inputs connected to 3 outputs (D,E,F) via a bottleneck (X), there are 3*3 routes = 9 routes.

A -->\ /--> D
B --> X --> E
C -->/ \--> F

If X is a storage, there are only 6 routes: A->X_o, B->X_o, C->X_o and X_i->D_o, X_i->E_o, X_i->F_o.

The BreakLink node is a compound node composed of a Storage with zero volume and a Link. It can be used in place of a normal Link, but with the benefit that it reduces the number of routes in the model (in the situation described above). The resulting LP is easier to solve.

__init__(model, name, **kwargs)

Initialise a new Node object

Parameters

modelModel

The model the node belongs to

namestring

A unique name for the node

Methods

__init__(model, name, **kwargs)	Initialise a new Node object
after(self, Timestep ts)
before(self, Timestep ts)	Called at the beginning of the timestep
check()	Check the node is valid
commit(self, int scenario_index, double value)	Called once for each route the node is a member of
commit_all(self, double[)	Called once for each route the node is a member of
connect(node[, from_slot, to_slot])	Create an edge from this Node to another Node
disconnect([node, slot_name, all_slots])	Remove a connection from this Node to another Node
finish(self)
get_conversion_factor(self)	Get the conversion factor
get_cost(self, ScenarioIndex scenario_index)	Get the cost per unit flow at a given timestep
get_max_flow(self, ScenarioIndex scenario_index)	Get the maximum flow at a given timestep
get_min_flow(self, ScenarioIndex scenario_index)	Get the minimum flow at a given timestep
iter_slots([slot_name, is_connector])	Returns the object(s) wich should be connected to given slot_name
load(data, model)
reset(self)	Called at the beginning of a run
setup(self, model)	Called before the first run of the model

Attributes

allow_isolated
comment	comment: basestring
component_attrs
components	Generator that returns all of the Components attached to the Node
conversion_factor	The conversion between inflow and outflow for the node
cost	The cost per unit flow via the node
domain
flow	Total flow via this node in the current timestep
fully_qualified_name
max_flow	The maximum flow constraint on the node
min_flow	The minimum flow constraint on the node
model	The recorder for the node, e.g.
name	Name of the node.
parent	The parent Node/Storage of this object.
prev_flow	Total flow via this node in the previous timestep
recorders	Returns a list of pywr.recorders.Recorder objects attached to this node.
virtual	virtual: ‘bool’