qiskit.chemistry.algorithms.pes_samplers.SieveExtrapolator
class SieveExtrapolator(extrapolator=None, window=2, filter_before=True, filter_after=True)
A wrapper extrapolator which clusters the parameter values - either before extrapolation, after, or both - into two large and small clusters, and sets the small clusters’ parameters to zero.
Constructor.
Parameters
- extrapolator (
Union[PolynomialExtrapolator,DifferentialExtrapolator,None]) – ‘internal’ extrapolator that performs extrapolation on variational parameters based on data window. - window (
int) – Number of previous points to use for extrapolation. - filter_before (
bool) – Keyword to perform clustering before extrapolation. - filter_after (
bool) – Keyword to perform clustering after extrapolation.
__init__
__init__(extrapolator=None, window=2, filter_before=True, filter_after=True)
Constructor.
Parameters
- extrapolator (
Union[PolynomialExtrapolator,DifferentialExtrapolator,None]) – ‘internal’ extrapolator that performs extrapolation on variational parameters based on data window. - window (
int) – Number of previous points to use for extrapolation. - filter_before (
bool) – Keyword to perform clustering before extrapolation. - filter_after (
bool) – Keyword to perform clustering after extrapolation.
Methods
__init__([extrapolator, window, …]) | Constructor. |
extrapolate(points, param_dict) | Extrapolate at specified point of interest given a set of variational parameters. |
factory(mode, **kwargs) | Factory method for constructing extrapolators. |
extrapolate
extrapolate(points, param_dict)
Extrapolate at specified point of interest given a set of variational parameters. Based on the specified window, a subset of the data points will be used for extrapolation. A default window of 2 points is used, while a value of zero indicates that all previous points will be used for extrapolation. This method finds a cutoff distance based on the maximum average distance or ‘gap’ between the average values of the variational parameters. This cutoff distance is used as a criteria to divide the parameters into two clusters by setting all parameters that are below the cutoff distance to zero.
Parameters
- points (
List[float]) – List of point(s) to be used for extrapolation. Can represent some degree of freedom, ex, interatomic distance. - param_dict (
Optional[Dict[float,List[float]]]) – Dictionary of variational parameters. Each key is the point and the value is a list of the variational parameters.
Return type
Dict[float, List[float]]
Returns
Dictionary of variational parameters for extrapolated point(s).
factory
static factory(mode, **kwargs)
Factory method for constructing extrapolators.
Parameters
- mode (
str) – Extrapolator to instantiate. Can be one of: - ‘window’ - ‘poly’ - ‘diff_model’ - ‘pca’ - ‘l1’ - kwargs – arguments to be passed to the constructor of an extrapolator
Return type
Extrapolator
Returns
A newly created extrapolator instance.
Raises
AquaError – if specified mode is unknown.