# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This module defines circular and circular-annulus apertures in both
pixel and sky coordinates.
"""
import math
from astropy.utils import lazyproperty
from photutils.aperture.attributes import (PixelPositions, PositiveScalar,
PositiveScalarAngle,
SkyCoordPositions)
from photutils.aperture.core import PixelAperture, SkyAperture
from photutils.aperture.mask import ApertureMask
from photutils.geometry import circular_overlap_grid
__all__ = ['CircularMaskMixin', 'CircularAperture', 'CircularAnnulus',
'SkyCircularAperture', 'SkyCircularAnnulus']
[docs]
class CircularMaskMixin:
"""
Mixin class to create masks for circular and circular-annulus
aperture objects.
"""
[docs]
def to_mask(self, method='exact', subpixels=5):
"""
Return a mask for the aperture.
Parameters
----------
method : {'exact', 'center', 'subpixel'}, optional
The method used to determine the overlap of the aperture on
the pixel grid. Not all options are available for all
aperture types. Note that the more precise methods are
generally slower. The following methods are available:
* ``'exact'`` (default):
The the exact fractional overlap of the aperture and
each pixel is calculated. The aperture weights will
contain values between 0 and 1.
* ``'center'``:
A pixel is considered to be entirely in or out of the
aperture depending on whether its center is in or out
of the aperture. The aperture weights will contain
values only of 0 (out) and 1 (in).
* ``'subpixel'``:
A pixel is divided into subpixels (see the
``subpixels`` keyword), each of which are considered
to be entirely in or out of the aperture depending
on whether its center is in or out of the aperture.
If ``subpixels=1``, this method is equivalent to
``'center'``. The aperture weights will contain values
between 0 and 1.
subpixels : int, optional
For the ``'subpixel'`` method, resample pixels by this
factor in each dimension. That is, each pixel is divided
into ``subpixels**2`` subpixels. This keyword is ignored
unless ``method='subpixel'``.
Returns
-------
mask : `~photutils.aperture.ApertureMask` or list of `~photutils.aperture.ApertureMask`
A mask for the aperture. If the aperture is scalar then a
single `~photutils.aperture.ApertureMask` is returned,
otherwise a list of `~photutils.aperture.ApertureMask` is
returned.
"""
use_exact, subpixels = self._translate_mask_mode(method, subpixels)
if hasattr(self, 'r'):
radius = self.r
elif hasattr(self, 'r_out'): # annulus
radius = self.r_out
else:
raise ValueError('Cannot determine the aperture radius.')
masks = []
for bbox, edges in zip(self._bbox, self._centered_edges):
ny, nx = bbox.shape
mask = circular_overlap_grid(edges[0], edges[1], edges[2],
edges[3], nx, ny, radius, use_exact,
subpixels)
# subtract the inner circle for an annulus
if hasattr(self, 'r_in'):
mask -= circular_overlap_grid(edges[0], edges[1], edges[2],
edges[3], nx, ny, self.r_in,
use_exact, subpixels)
masks.append(ApertureMask(mask, bbox))
if self.isscalar:
return masks[0]
else:
return masks
[docs]
class CircularAperture(CircularMaskMixin, PixelAperture):
"""
A circular aperture defined in pixel coordinates.
The aperture has a single fixed size/shape, but it can have multiple
positions (see the ``positions`` input).
Parameters
----------
positions : array_like
The pixel coordinates of the aperture center(s) in one of the
following formats:
* single ``(x, y)`` pair as a tuple, list, or `~numpy.ndarray`
* tuple, list, or `~numpy.ndarray` of ``(x, y)`` pairs
r : float
The radius of the circle in pixels.
Raises
------
ValueError : `ValueError`
If the input radius, ``r``, is negative.
Examples
--------
>>> from photutils.aperture import CircularAperture
>>> aper = CircularAperture([10.0, 20.0], 3.0)
>>> aper = CircularAperture((10.0, 20.0), 3.0)
>>> pos1 = (10.0, 20.0) # (x, y)
>>> pos2 = (30.0, 40.0)
>>> pos3 = (50.0, 60.0)
>>> aper = CircularAperture([pos1, pos2, pos3], 3.0)
>>> aper = CircularAperture((pos1, pos2, pos3), 3.0)
"""
_params = ('positions', 'r')
positions = PixelPositions('The center pixel position(s).')
r = PositiveScalar('The radius in pixels.')
def __init__(self, positions, r):
self.positions = positions
self.r = r
@lazyproperty
def _xy_extents(self):
return self.r, self.r
@lazyproperty
def area(self):
return math.pi * self.r**2
def _to_patch(self, origin=(0, 0), **kwargs):
"""
Return a `~matplotlib.patches.patch` for the aperture.
Parameters
----------
origin : array_like, optional
The ``(x, y)`` position of the origin of the displayed
image.
**kwargs : `dict`
Any keyword arguments accepted by
`matplotlib.patches.Patch`.
Returns
-------
patch : `~matplotlib.patches.patch` or list of `~matplotlib.patches.patch`
A patch for the aperture. If the aperture is scalar then a
single `~matplotlib.patches.patch` is returned, otherwise a
list of `~matplotlib.patches.patch` is returned.
"""
import matplotlib.patches as mpatches
xy_positions, patch_kwargs = self._define_patch_params(origin=origin,
**kwargs)
patches = []
for xy_position in xy_positions:
patches.append(mpatches.Circle(xy_position, self.r,
**patch_kwargs))
if self.isscalar:
return patches[0]
else:
return patches
[docs]
def to_mask(self, method='exact', subpixels=5):
return CircularMaskMixin.to_mask(self, method=method,
subpixels=subpixels)
[docs]
def to_sky(self, wcs):
"""
Convert the aperture to a `SkyCircularAperture` object defined
in celestial coordinates.
Parameters
----------
wcs : WCS object
A world coordinate system (WCS) transformation that
supports the `astropy shared interface for WCS
<https://docs.astropy.org/en/stable/wcs/wcsapi.html>`_
(e.g., `astropy.wcs.WCS`, `gwcs.wcs.WCS`).
Returns
-------
aperture : `SkyCircularAperture` object
A `SkyCircularAperture` object.
"""
return SkyCircularAperture(**self._to_sky_params(wcs))
[docs]
class CircularAnnulus(CircularMaskMixin, PixelAperture):
"""
A circular annulus aperture defined in pixel coordinates.
The aperture has a single fixed size/shape, but it can have multiple
positions (see the ``positions`` input).
Parameters
----------
positions : array_like
The pixel coordinates of the aperture center(s) in one of the
following formats:
* single ``(x, y)`` pair as a tuple, list, or `~numpy.ndarray`
* tuple, list, or `~numpy.ndarray` of ``(x, y)`` pairs
r_in : float
The inner radius of the circular annulus in pixels.
r_out : float
The outer radius of the circular annulus in pixels.
Raises
------
ValueError : `ValueError`
If inner radius (``r_in``) is greater than outer radius (``r_out``).
ValueError : `ValueError`
If inner radius (``r_in``) is negative.
Examples
--------
>>> from photutils.aperture import CircularAnnulus
>>> aper = CircularAnnulus([10.0, 20.0], 3.0, 5.0)
>>> aper = CircularAnnulus((10.0, 20.0), 3.0, 5.0)
>>> pos1 = (10.0, 20.0) # (x, y)
>>> pos2 = (30.0, 40.0)
>>> pos3 = (50.0, 60.0)
>>> aper = CircularAnnulus([pos1, pos2, pos3], 3.0, 5.0)
>>> aper = CircularAnnulus((pos1, pos2, pos3), 3.0, 5.0)
"""
_params = ('positions', 'r_in', 'r_out')
positions = PixelPositions('The center pixel position(s).')
r_in = PositiveScalar('The inner radius in pixels.')
r_out = PositiveScalar('The outer radius in pixels.')
def __init__(self, positions, r_in, r_out):
if not r_out > r_in:
raise ValueError('r_out must be greater than r_in')
self.positions = positions
self.r_in = r_in
self.r_out = r_out
@lazyproperty
def _xy_extents(self):
return self.r_out, self.r_out
@lazyproperty
def area(self):
return math.pi * (self.r_out**2 - self.r_in**2)
def _to_patch(self, origin=(0, 0), **kwargs):
"""
Return a `~matplotlib.patches.patch` for the aperture.
Parameters
----------
origin : array_like, optional
The ``(x, y)`` position of the origin of the displayed
image.
**kwargs : `dict`
Any keyword arguments accepted by
`matplotlib.patches.Patch`.
Returns
-------
patch : `~matplotlib.patches.patch` or list of `~matplotlib.patches.patch`
A patch for the aperture. If the aperture is scalar then a
single `~matplotlib.patches.patch` is returned, otherwise a
list of `~matplotlib.patches.patch` is returned.
"""
import matplotlib.patches as mpatches
xy_positions, patch_kwargs = self._define_patch_params(origin=origin,
**kwargs)
patches = []
for xy_position in xy_positions:
patch_inner = mpatches.Circle(xy_position, self.r_in)
patch_outer = mpatches.Circle(xy_position, self.r_out)
path = self._make_annulus_path(patch_inner, patch_outer)
patches.append(mpatches.PathPatch(path, **patch_kwargs))
if self.isscalar:
return patches[0]
else:
return patches
[docs]
def to_mask(self, method='exact', subpixels=5):
return CircularMaskMixin.to_mask(self, method=method,
subpixels=subpixels)
[docs]
def to_sky(self, wcs):
"""
Convert the aperture to a `SkyCircularAnnulus` object defined
in celestial coordinates.
Parameters
----------
wcs : WCS object
A world coordinate system (WCS) transformation that
supports the `astropy shared interface for WCS
<https://docs.astropy.org/en/stable/wcs/wcsapi.html>`_
(e.g., `astropy.wcs.WCS`, `gwcs.wcs.WCS`).
Returns
-------
aperture : `SkyCircularAnnulus` object
A `SkyCircularAnnulus` object.
"""
return SkyCircularAnnulus(**self._to_sky_params(wcs))
[docs]
class SkyCircularAperture(SkyAperture):
"""
A circular aperture defined in sky coordinates.
The aperture has a single fixed size/shape, but it can have multiple
positions (see the ``positions`` input).
Parameters
----------
positions : `~astropy.coordinates.SkyCoord`
The celestial coordinates of the aperture center(s). This can be
either scalar coordinates or an array of coordinates.
r : scalar `~astropy.units.Quantity`
The radius of the circle in angular units.
Examples
--------
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils.aperture import SkyCircularAperture
>>> positions = SkyCoord(ra=[10.0, 20.0], dec=[30.0, 40.0], unit='deg')
>>> aper = SkyCircularAperture(positions, 0.5*u.arcsec)
"""
_params = ('positions', 'r',)
positions = SkyCoordPositions('The center position(s) in sky coordinates.')
r = PositiveScalarAngle('The radius in angular units.')
def __init__(self, positions, r):
self.positions = positions
self.r = r
[docs]
def to_pixel(self, wcs):
"""
Convert the aperture to a `CircularAperture` object defined in
pixel coordinates.
Parameters
----------
wcs : WCS object
A world coordinate system (WCS) transformation that
supports the `astropy shared interface for WCS
<https://docs.astropy.org/en/stable/wcs/wcsapi.html>`_
(e.g., `astropy.wcs.WCS`, `gwcs.wcs.WCS`).
Returns
-------
aperture : `CircularAperture` object
A `CircularAperture` object.
"""
return CircularAperture(**self._to_pixel_params(wcs))
[docs]
class SkyCircularAnnulus(SkyAperture):
"""
A circular annulus aperture defined in sky coordinates.
The aperture has a single fixed size/shape, but it can have multiple
positions (see the ``positions`` input).
Parameters
----------
positions : `~astropy.coordinates.SkyCoord`
The celestial coordinates of the aperture center(s). This can be
either scalar coordinates or an array of coordinates.
r_in : scalar `~astropy.units.Quantity`
The inner radius of the circular annulus in angular units.
r_out : scalar `~astropy.units.Quantity`
The outer radius of the circular annulus in angular units.
Examples
--------
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils.aperture import SkyCircularAnnulus
>>> positions = SkyCoord(ra=[10.0, 20.0], dec=[30.0, 40.0], unit='deg')
>>> aper = SkyCircularAnnulus(positions, 0.5*u.arcsec, 1.0*u.arcsec)
"""
_params = ('positions', 'r_in', 'r_out')
positions = SkyCoordPositions('The center position(s) in sky coordinates.')
r_in = PositiveScalarAngle('The inner radius in angular units.')
r_out = PositiveScalarAngle('The outer radius in angular units.')
def __init__(self, positions, r_in, r_out):
if r_in.unit.physical_type != r_out.unit.physical_type:
raise ValueError('r_in and r_out should either both be angles '
'or in pixels.')
self.positions = positions
self.r_in = r_in
self.r_out = r_out
[docs]
def to_pixel(self, wcs):
"""
Convert the aperture to a `CircularAnnulus` object defined in
pixel coordinates.
Parameters
----------
wcs : WCS object
A world coordinate system (WCS) transformation that
supports the `astropy shared interface for WCS
<https://docs.astropy.org/en/stable/wcs/wcsapi.html>`_
(e.g., `astropy.wcs.WCS`, `gwcs.wcs.WCS`).
Returns
-------
aperture : `CircularAnnulus` object
A `CircularAnnulus` object.
"""
return CircularAnnulus(**self._to_pixel_params(wcs))