# LSST Data Management System
# Copyright 2016 AURA/LSST.
#
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
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from __future__ import print_function, absolute_import
import numpy as np
from ..base import MeasurementBase, Metric
[docs]class AFxMeasurement(MeasurementBase):
"""Measurement of AFx (x=1,2,3): The maximum fraction of astrometric
distances which deviate by more than ADx milliarcsec (see AMx) (%).
Parameters
----------
x : int
Variant of AMx metric (x=1, 2, 3), which in turn sets the radius
of the annulus for selecting pairs of stars.
matchedDataset : lsst.validate.drp.matchreduce.MatchedMultiVisitDataset
amx : :class:`lsst.validate.drp.calcsrd.AMxMeasurement`
And AMx measurement, providing the median astrometric scatter in
the annulus.
bandpass : str
Bandpass (filter name) used in this measurement (e.g., `'r'`).
specName : str
Name of a specification level to measure against (e.g., design,
minimum, stretch).
verbose : bool, optional
Output additional information on the analysis steps.
job : :class:`lsst.validate.drp.base.Job`, optional
If provided, the measurement will register itself with the Job
object.
linkedBlobs : dict, optional
A `dict` of additional blobs (subclasses of BlobBase) that
can provide additional context to the measurement, though aren't
direct dependencies of the computation (e.g., `matchedDataset).
Raises
------
ValueError
If `x` isn't in [1, 2, 3].
Notes
-----
This table below is provided ``validate_drp``\ 's :file:`metrics.yaml`.
LPM-17 dated 2011-07-06
Specification:
The rms of the astrometric distance distribution for
stellar pairs with separation of D arcmin (repeatability)
will not exceed AMx milliarcsec (median distribution for a large number
of sources). No more than AFx % of the sample will deviate by more than
ADx milliarcsec from the median. AMx, AFx, and ADx are specified for
D=5, 20 and 200 arcmin for x= 1, 2, and 3, in the same order (Table 18).
The three selected characteristic distances reflect the size of an
individual sensor, a raft, and the camera. The required median astrometric
precision is driven by the desire to achieve a proper motion accuracy of
0.2 mas/yr and parallax accuracy of 1.0 mas over the course of the survey.
These two requirements correspond to relative astrometric precision for a
single image of 10 mas (per coordinate).
========================= ====== ======= =======
Astrometric Repeatability Specification
------------------------- ----------------------
Metric Design Minimum Stretch
========================= ====== ======= =======
AM1 (milliarcsec) 10 20 5
AF1 (%) 10 20 5
AD1 (milliarcsec) 20 40 10
AM2 (milliarcsec) 10 20 5
AF2 (%) 10 20 5
AD2 (milliarcsec) 20 40 10
AM3 (milliarcsec) 15 30 10
AF3 (%) 10 20 5
AD3 (milliarcsec) 30 50 20
========================= ====== ======= =======
Table 18: The specifications for astrometric precision.
The three blocks of values correspond to D=5, 20 and 200 arcmin,
and to astrometric measurements performed in the r and i bands.
"""
metric = None
value = None
units = ''
label = 'AFx'
def __init__(self, x, matchedDataset, amx, bandpass, specName,
verbose=False, job=None,
linkedBlobs=None, metricYamlDoc=None, metricYamlPath=None):
MeasurementBase.__init__(self)
if x not in [1, 2, 3]:
raise ValueError('AFx x should be 1, 2, or 3.')
self.label = 'AF{0:d}'.format(x)
self.specName = specName
self.bandpass = bandpass
self.metric = Metric.fromYaml(self.label,
yamlDoc=metricYamlDoc,
yamlPath=metricYamlPath)
# register input parameters for serialization
# note that matchedDataset is treated as a blob, separately
self.registerParameter('D', datum=amx.parameters['D'])
self.registerParameter('annulus', datum=amx.parameters['annulus'])
self.registerParameter('magRange', datum=amx.parameters['magRange'])
self.registerParameter('AMx', datum=amx.datum)
self.matchedDataset = matchedDataset
# Add external blob so that links will be persisted with
# the measurement
if linkedBlobs is not None:
for name, blob in linkedBlobs.items():
setattr(self, name, blob)
adx = getattr(self.metric.getSpec(specName, bandpass=self.bandpass),
'AD{0:d}'.format(x))\
.getSpec(specName, bandpass=self.bandpass)
self.registerParameter('ADx', datum=adx.datum)
if amx.value:
self.value = 100. * np.mean(amx.rmsDistMas > amx.value + self.ADx)
else:
# FIXME previously would raise ValidateErrorNoStars
self.value = None
if job:
job.registerMeasurement(self)