andes.core.service.BackRef

class andes.core.service.BackRef(**kwargs)

A special type of reference collector.

BackRef is used for collecting device indices of other models referencing the parent model of the BackRef. The v``field will be a list of lists, each containing the `idx of other models referencing each device of the parent model.

BackRef can be passed as indexer for params and vars, or shape for NumReduce and NumRepeat. See examples for illustration.

See also

andes.core.service.NumReduce

A more complete example using BackRef to build the COI model

Examples

A Bus device has an IdxParam of area, storing the idx of area to which the bus device belongs. In Bus.__init__(), one has

self.area = IdxParam(model='Area')

Suppose Bus has the following data

idx	area	Vn
1	1	110
2	2	220
3	1	345
4	1	500

The Area model wants to collect the indices of Bus devices which points to the corresponding Area device. In Area.__init__, one defines

self.Bus = BackRef()

where the member attribute name Bus needs to match exactly model name that Area wants to collect idx for. Similarly, one can define self.ACNode = BackRef() to collect devices in the ACNode group that references Area.

The collection of idx happens in andes.system.System._collect_ref_param(). It has to be noted that the specific Area entry must exist to collect model idx-dx referencing it. For example, if Area has the following data

idx 1

Then, only Bus 1, 3, and 4 will be collected into self.Bus.v, namely, self.Bus.v == [ [1, 3, 4] ].

If Area has data

idx 1 2

Then, self.Bus.v will end up with [ [1, 3, 4], [2] ].

__init__(**kwargs)

Methods

assign_memory(n)	Assign memory for self.v and set the array to zero.
get_names()	Return name in a list

Attributes

class_name	Return the class name
n	Return the count of values in self.v.