cunqa.mappers.QJobMapper

class cunqa.mappers.QJobMapper(qjobs: list[QJob])

Bases: object

Class to map the method upgrade_parameters() to a set of jobs sent to virtual QPUs.

The core of the class is on its __call__() method, to which parameters that the method upgrade_parameters() takes are passed toguether with a cost function, so that a the value for this cost for each initial QJob is returned.

An example is shown below, once we have a list of QJob objects as qjobs:

>>> mapper = QJobMapper(qjobs)
>>>
>>> # defining the parameters set accordingly to the number of parameters
>>> # of the circuit and the number of QJobs in the list.
>>> new_parameters = [...]
>>>
>>> # defining the cost function passed to the result of each QJob
>>> def cost_function(result):
>>>     counts = result.counts
>>>     ...
>>>     return cost_value
>>>
>>> cost_values = mapper(cost_function, new_parameters)

We intuitively see how convinient this class can be for optimization algorithms: one has a parametric circuit to which updated sets of parameters can be sent obtaining the value of the cost back. Examples applied to optimizations are shown at the Examples gallery.

Attributes

qjobs

List of jobs that are mapped.

Methods

QJobMapper.__init__(qjobs: list[QJob])

Class constructor.

Parameters:

qjobs (list[QJob]) – list of QJob objects to be mapped.

QJobMapper.__call__(func, population)

Callable method to map the function func to the results of assigning population to the given jobs. Regarding the population, each set of parameters will be assigned to each QJob object, so the list must have size (N,p), being N the lenght of qjobs and p the number of parameters in the circuit. Mainly, this is thought for the function to take a Result object and to return a value. For example, the function can evaluate the expected value of an observable from the output of the circuit.

Parameters:

• func (callable) – function to be passed to the results of the jobs.

• population (list[list[int | float]]) – list of vectors to be mapped to the jobs.

Returns:

List of outputs of the function applied to the results of each job for the given population.