Inheritance diagram for lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask:

Public Member Functions
	__init__ (self, ComputeRoughPsfShapeletsConfig\|None config=None, , Schema schema, *Any kwargs)

Struct	run (self, *, MaskedImageF masked_image, SourceCatalog catalog, int seed)

dict[int, SpanSetMoments]	compute_raw_moments (self, *, MaskedImageF masked_image, SourceCatalog catalog)

Struct	select_stars (self, SourceCatalog catalog, int seed)

None	plot_selection (self, matplotlib.figure.Figure figure, *, SourceCatalog catalog, Struct results)

None	plot_shapelets (self, matplotlib.figure.Figure figure, *, ImageF image, SourceCatalog catalog, Struct results, int n_stars=3, float stamp_size=2.0)

Public Attributes
	schema = schema

Static Public Attributes
	ConfigClass = ComputeRoughPsfShapeletsConfig

Protected Member Functions
np.ndarray	_threshold_with_bounds (self, np.ndarray values, float threshold, int min_count, int max_count, str name, Literal["<", ">"] kind)

tuple[float, KernelDensity]	_find_first_radius_mode (self, np.ndarray radii)

Static Protected Member Functions
matplotlib.patches.Ellipse	_draw_ellipse (matplotlib.axes.Axes axes, ellipses.BaseCore\|ellipses.Ellipse ellipse, , float\|None x=None, float\|None y=None, float scale=1.0, *Any kwargs)

matplotlib.image.AxesImage	_draw_image (matplotlib.axes.Axes axes, ImageF image, **Any kwargs)

Protected Attributes
	_flux_key = schema.addField("RawPsfMoments_flux", type=float, doc="Unweighted zeroth moment.")

	_flux_err_key

	_center_key

	_shape_key

	_flag_key

	_candidate_key

	_used_key

Static Protected Attributes
str	_DefaultName = "computeRoughPsfShapelets"

Detailed Description

A task that computes a rough shapelet expansion of the PSF from a set
of high S/N detections.

Notes
-----
This task is expected to be run early in single-epoch processing - just
after background subtraction and an initial high S/N detection phase, and
before any deblending or measurement - in order to identify out-of-focus
or otherwise bad PSFs.

Given a background-subtracted `lsst.afw.image.MaskedImage`, an
`lsst.afw.table.SourceCatalog` with footprints attached, and a random
number generator seed, the `run` method will:

- Compute the *unweighted* 0th-2nd moments of every non-child source over
  the footprint (except certain configurable masked pixels).  This is
  delegated to the `compute_raw_moments` method (which uses the C++
  `SpanSetMoments` class for the pixel-level processing).  Unweighted
  moments are used to avoid "latching onto" a small piece of PSF
  substructure, but can be much noiser than the Gaussian-weighed moments
  we usually use.

- Select a "candidate" sample of sources with successfully measured
  moments that satisfy a S/N cut and a radius cut (determined from the
  first mode of the radius distribution, via kernel density estimation),
  and then use a robust covariance estimator (`scikit_learn.MinCovDet`)
  to select presumed isolated stars that are close to the center of that
  distribution, in 3-parameter shape space. This is delegated to the
  `select_stars` method.

- Fit a single shapelet expansion to the selected stars.  This is
  mostly delegated to the `SpanSetMoments.fit_shapelets` method.

The radial shapelet terms at 0th, 2nd, and 4th order are expected to form
a space in which donut-shaped PSFs are well-separated from those with
monotonic profiles.  Other terms *may* be useful in identifying other
kinds of undesirable PSF structure.

Definition at line 158 of file computeRoughPsfShapelets.py.

Constructor & Destructor Documentation

◆ init()

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.__init__	(		self,
		ComputeRoughPsfShapeletsConfig \| None	config = None,
		*	,
		Schema	schema,
		**Any	kwargs )

Definition at line 202 of file computeRoughPsfShapelets.py.

Member Function Documentation

◆ _draw_ellipse()

matplotlib.patches.Ellipse lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._draw_ellipse	(	matplotlib.axes.Axes	axes,
		ellipses.BaseCore \| ellipses.Ellipse	ellipse,
		*	,
		float \| None	x = None,
		float \| None	y = None,
		float	scale = 1.0,
		**Any	kwargs )

staticprotected

Definition at line 748 of file computeRoughPsfShapelets.py.

◆ _draw_image()

matplotlib.image.AxesImage lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._draw_image	(	matplotlib.axes.Axes	axes,
		ImageF	image,
		**Any	kwargs )

staticprotected

Definition at line 782 of file computeRoughPsfShapelets.py.

◆ _find_first_radius_mode()

tuple[float, KernelDensity] lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._find_first_radius_mode	(		self,
		np.ndarray	radii )

protected

Find the first peak in a 1-d distribution of radii.

Definition at line 735 of file computeRoughPsfShapelets.py.

◆ _threshold_with_bounds()

np.ndarray lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._threshold_with_bounds	(		self,
		np.ndarray	values,
		float	threshold,
		int	min_count,
		int	max_count,
		str	name,
		Literal["<", ">"]	kind )

protected

Return the indices of an array that satisfy an inequality
and/or lower and upper bounds on the number of indices returned.

Parameters
----------
values
    Array of values to threshold on.
threshold
    Threshold value that selected elements must be above or below.
min_count
    The minimum number of indices returned.  When thresholding would
    yield fewer than this number, the threshold is ignored.  Note that
    the number of indices may still be less than this if the size of
    ``values`` is less than this.
max_count
    The maximum number of indices returned.
name
    Name of the quantity being thresholded, for log messages.
kind
    Whether the threshold is a upper bound (``<``) or lower bound
    (``>``).  This also sets how values are ranked when they are added
    or dropped to satisfy the count constraints.

Returns
-------
indices
    Indices into ``values``.

Definition at line 659 of file computeRoughPsfShapelets.py.

◆ compute_raw_moments()

dict[int, SpanSetMoments] lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.compute_raw_moments	(		self,
		*	,
		MaskedImageF	masked_image,
		SourceCatalog	catalog )

Compute the unweighted moments of the footprints in a catalog.

Parameters
----------
masked_image
    Masked image to measure on.  Must be background-subtracted.
catalog
    Catalog of detections to extract footprints from and fill output
    columns of.  Its schema must be a superset of ``self.schema``.

Returns
-------
`dict` [`int`, `SpanSetMoments`]
    Objects used to construct and hold the unweighted moments and the
    pixel region used to computed them, keyed by source ID.

Definition at line 285 of file computeRoughPsfShapelets.py.

◆ plot_selection()

None lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.plot_selection	(		self,
		matplotlib.figure.Figure	figure,
		*	,
		SourceCatalog	catalog,
		Struct	results )

Create plots of the shape distribution space used to select stars.

Parameters
----------
figure
    Matplotlib figure to plot to.
catalog
    Catalog of sources with columns populated by the `run` method (at
    least through the `select_stars` step).
results
    Result struct returned by `run` or `select_stars`.

Definition at line 441 of file computeRoughPsfShapelets.py.

◆ plot_shapelets()

None lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.plot_shapelets	(		self,
		matplotlib.figure.Figure	figure,
		*	,
		ImageF	image,
		SourceCatalog	catalog,
		Struct	results,
		int	n_stars = 3,
		float	stamp_size = 2.0 )

Create data/model/residual plots of stars and the shapelet model.

Parameters
----------
figure
    Matplotlib figure to plot to.
image
    The image the stars were measured on.
catalog
    Catalog of sources with columns populated by the `run` method .
results
    Result struct returned by `run`.
n_stars
    Number of stars to include.
stamp_size
    Stamp size in inches.

Definition at line 586 of file computeRoughPsfShapelets.py.

◆ run()

Struct lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.run	(		self,
		*	,
		MaskedImageF	masked_image,
		SourceCatalog	catalog,
		int	seed )

Compute raw moments, select stars, and fit a shapelet expansion to
them.

Parameters
----------
masked_image
    Masked image to measure on.  Must be background-subtracted.
catalog
    Catalog of detections to extract footprints from and fill output
    columns of.  Its schema must be a superset of ``self.schema``.
seed
    A random-number generator seed, used for the robust covariance
    estimator.

Returns
-------
`lsst.pipe.base.Struct`
    A struct of results containing:

    - ``shapelet`` (`lsst.shapelet.ShapeletFunction`): A
      Gauss-Laguerre (polar shaplet) expansion of the PSF.
    - ``radial`` (`list` [`float`]): the purely radial coefficients
      of the shapelet expansion.
    - all attributes returned by the `select_stars` method.

Definition at line 242 of file computeRoughPsfShapelets.py.

◆ select_stars()

Struct lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.select_stars	(		self,
		SourceCatalog	catalog,
		int	seed )

Select probable stars from the distribution of second moments.

Parameters
----------
catalog
    Catalog of detections to extract footprints from and fill output
    columns of.  Its schema must be a superset of ``self.schema``.
seed
    A random-number generator seed, used for the robust covariance
    estimator.

Returns
-------
`lsst.pipe.base.Struct`
    A struct of results containing:

    - ``star_ids`` (`numpy.ndarray`): the source IDs that are expected
      to be stars.
    - ``mean_shape`` (`lsst.afw.geom.ellipses.BaseCore`): the mean of
      the shape distribution.
    - ``shape_covariance`` (`numpy.ndarray`): the covariance of the
      distribution of shapes; a 3x3 matrix.  This uses the same
      parameterization of the shapes as ``mean_shape``.
    - ``radius_cut`` (`float`): the indended radius cut (i.e. the
      mode of the radius distribution multipled by the
      ``radius_factor`` configuration option).
    - ``radius_kde`` (`sklearn.neighbors.KernelDensity`): kernel
      density estimator on the radius distribution, used to determine
      the radius cut.

Definition at line 345 of file computeRoughPsfShapelets.py.

Member Data Documentation

◆ _candidate_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._candidate_key

protected

Initial value:

=  schema.addField(
            "RoughPsfShapelets_candidate",
            type="Flag",
            doc="Flag set if this source passed the radius_fraction cut (see configuration).",
        )

Definition at line 228 of file computeRoughPsfShapelets.py.

◆ _center_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._center_key

protected

Initial value:

=  Point2DKey.addFields(
            schema, "RoughPsfShapelets", "Center from unweighted first moments.", "pixels"
        )

Definition at line 217 of file computeRoughPsfShapelets.py.

◆ _DefaultName

str lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._DefaultName = "computeRoughPsfShapelets"

staticprotected

Definition at line 199 of file computeRoughPsfShapelets.py.

◆ _flag_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._flag_key

protected

Initial value:

=  schema.addField(
            "RoughPsfShapelets_flag",
            type="Flag",
            doc="Flag set if the raw PSF moments were not computed.",
        )

Definition at line 223 of file computeRoughPsfShapelets.py.

◆ _flux_err_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._flux_err_key

protected

Initial value:

=  schema.addField(
            "RoughPsfShapelets_fluxErr",
            type=float,
            doc="Uncertainty on the unweighted zeroth moment.",
        )

Definition at line 212 of file computeRoughPsfShapelets.py.

◆ _flux_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._flux_key = schema.addField("RawPsfMoments_flux", type=float, doc="Unweighted zeroth moment.")

protected

Definition at line 211 of file computeRoughPsfShapelets.py.

◆ _shape_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._shape_key

protected

Initial value:

=  QuadrupoleKey.addFields(
            schema, "RoughPsfShapelets", "Shape from unweighted second moments."
        )

Definition at line 220 of file computeRoughPsfShapelets.py.

◆ _used_key

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask._used_key

protected

Initial value:

=  schema.addField(
            "RoughPsfShapelets_used",
            type="Flag",
            doc=(
                "Flag set if this source passed the radius_fraction and shape_distance cuts "
                "(see configuration) and was used to fit the shapelet expansion."
            ),
        )

Definition at line 233 of file computeRoughPsfShapelets.py.

◆ ConfigClass

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.ConfigClass = ComputeRoughPsfShapeletsConfig

static

Definition at line 198 of file computeRoughPsfShapelets.py.

◆ schema

lsst.meas.algorithms.computeRoughPsfShapelets.ComputeRoughPsfShapeletsTask.schema = schema

Definition at line 210 of file computeRoughPsfShapelets.py.

The documentation for this class was generated from the following file:

python/lsst/meas/algorithms/computeRoughPsfShapelets.py

Public Member Functions

Public Attributes

Static Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ __init__()

Member Function Documentation

◆ _draw_ellipse()

◆ _draw_image()

◆ _find_first_radius_mode()

◆ _threshold_with_bounds()

◆ compute_raw_moments()

◆ plot_selection()

◆ plot_shapelets()

◆ run()

◆ select_stars()

Member Data Documentation

◆ _candidate_key

◆ _center_key

◆ _DefaultName

◆ _flag_key

◆ _flux_err_key

◆ _flux_key

◆ _shape_key

◆ _used_key

◆ ConfigClass

◆ schema

◆ init()