# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This module defines rectangular and rectangular-annulus apertures in
both pixel and sky coordinates.
"""
import math
import astropy.units as u
import numpy as np
from photutils.aperture.attributes import (PixelPositions, PositiveScalar,
PositiveScalarAngle, ScalarAngle,
ScalarAngleOrValue,
SkyCoordPositions)
from photutils.aperture.core import PixelAperture, SkyAperture
from photutils.aperture.mask import ApertureMask
from photutils.geometry import rectangular_overlap_grid
__all__ = ['RectangularMaskMixin', 'RectangularAperture',
'RectangularAnnulus', 'SkyRectangularAperture',
'SkyRectangularAnnulus']
[docs]
class RectangularMaskMixin:
"""
Mixin class to create masks for rectangular or rectangular-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.
"""
_, subpixels = self._translate_mask_mode(method, subpixels,
rectangle=True)
if hasattr(self, 'w'):
w = self.w
h = self.h
elif hasattr(self, 'w_out'): # annulus
w = self.w_out
h = self.h_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 = rectangular_overlap_grid(edges[0], edges[1], edges[2],
edges[3], nx, ny, w, h,
self._theta_radians, 0, subpixels)
# subtract the inner circle for an annulus
if hasattr(self, 'w_in'):
mask -= rectangular_overlap_grid(edges[0], edges[1], edges[2],
edges[3], nx, ny, self.w_in,
self.h_in,
self._theta_radians, 0,
subpixels)
masks.append(ApertureMask(mask, bbox))
if self.isscalar:
return masks[0]
else:
return masks
@staticmethod
def _calc_extents(width, height, theta):
"""
Calculate half of the bounding box extents of an ellipse.
"""
half_width = width / 2.0
half_height = height / 2.0
sin_theta = math.sin(theta)
cos_theta = math.cos(theta)
x_extent1 = abs((half_width * cos_theta) - (half_height * sin_theta))
x_extent2 = abs((half_width * cos_theta) + (half_height * sin_theta))
y_extent1 = abs((half_width * sin_theta) + (half_height * cos_theta))
y_extent2 = abs((half_width * sin_theta) - (half_height * cos_theta))
x_extent = max(x_extent1, x_extent2)
y_extent = max(y_extent1, y_extent2)
return x_extent, y_extent
@staticmethod
def _lower_left_positions(positions, width, height, theta):
"""
Calculate lower-left positions from the input center positions.
Used for creating `~matplotlib.patches.Rectangle` patch for the
aperture.
"""
half_width = width / 2.0
half_height = height / 2.0
sin_theta = math.sin(theta)
cos_theta = math.cos(theta)
xshift = (half_height * sin_theta) - (half_width * cos_theta)
yshift = -(half_height * cos_theta) - (half_width * sin_theta)
return np.atleast_2d(positions) + np.array([xshift, yshift])
[docs]
class RectangularAperture(RectangularMaskMixin, PixelAperture):
"""
A rectangular 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
w : float
The full width of the rectangle in pixels. For ``theta=0`` the
width side is along the ``x`` axis.
h : float
The full height of the rectangle in pixels. For ``theta=0`` the
height side is along the ``y`` axis.
theta : float or `~astropy.units.Quantity`, optional
The rotation angle as an angular quantity
(`~astropy.units.Quantity` or `~astropy.coordinates.Angle`) or
value in radians (as a float) from the positive ``x`` axis. The
rotation angle increases counterclockwise.
Raises
------
ValueError : `ValueError`
If either width (``w``) or height (``h``) is negative.
Examples
--------
>>> from astropy.coordinates import Angle
>>> from photutils.aperture import RectangularAperture
>>> theta = Angle(80, 'deg')
>>> aper = RectangularAperture([10.0, 20.0], 5.0, 3.0)
>>> aper = RectangularAperture((10.0, 20.0), 5.0, 3.0, theta=theta)
>>> pos1 = (10.0, 20.0) # (x, y)
>>> pos2 = (30.0, 40.0)
>>> pos3 = (50.0, 60.0)
>>> aper = RectangularAperture([pos1, pos2, pos3], 5.0, 3.0)
>>> aper = RectangularAperture((pos1, pos2, pos3), 5.0, 3.0, theta=theta)
"""
_params = ('positions', 'w', 'h', 'theta')
positions = PixelPositions('The center pixel position(s).')
w = PositiveScalar('The full width in pixels.')
h = PositiveScalar('The full height in pixels.')
theta = ScalarAngleOrValue('The counterclockwise rotation angle as an '
'angular Quantity or value in radians from '
'the positive x axis.')
def __init__(self, positions, w, h, theta=0.0):
self.positions = positions
self.w = w
self.h = h
self._theta_radians = 0.0 # defined by theta setter
self.theta = theta
@property
def _xy_extents(self):
return self._calc_extents(self.w, self.h, self._theta_radians)
@property
def area(self):
return self.w * self.h
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)
xy_positions = self._lower_left_positions(xy_positions, self.w,
self.h, self._theta_radians)
patches = []
theta_deg = self._theta_radians * 180.0 / np.pi
for xy_position in xy_positions:
patches.append(mpatches.Rectangle(xy_position, self.w, self.h,
angle=theta_deg, **patch_kwargs))
if self.isscalar:
return patches[0]
else:
return patches
[docs]
def to_mask(self, method='exact', subpixels=5):
return RectangularMaskMixin.to_mask(self, method=method,
subpixels=subpixels)
[docs]
def to_sky(self, wcs):
"""
Convert the aperture to a `SkyRectangularAperture` 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 : `SkyRectangularAperture` object
A `SkyRectangularAperture` object.
"""
return SkyRectangularAperture(**self._to_sky_params(wcs))
[docs]
class RectangularAnnulus(RectangularMaskMixin, PixelAperture):
r"""
A rectangular 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
w_in : float
The inner full width of the rectangular annulus in pixels. For
``theta=0`` the width side is along the ``x`` axis.
w_out : float
The outer full width of the rectangular annulus in pixels. For
``theta=0`` the width side is along the ``x`` axis.
h_out : float
The outer full height of the rectangular annulus in pixels.
h_in : `None` or float
The inner full height of the rectangular annulus in pixels.
If `None`, then the inner full height is calculated as:
.. math:: h_{in} = h_{out}
\left(\frac{w_{in}}{w_{out}}\right)
For ``theta=0`` the height side is along the ``y`` axis.
theta : float or `~astropy.units.Quantity`, optional
The rotation angle as an angular quantity
(`~astropy.units.Quantity` or `~astropy.coordinates.Angle`) or
value in radians (as a float) from the positive ``x`` axis. The
rotation angle increases counterclockwise.
Raises
------
ValueError : `ValueError`
If inner width (``w_in``) is greater than outer width
(``w_out``).
ValueError : `ValueError`
If either the inner width (``w_in``) or the outer height
(``h_out``) is negative.
Examples
--------
>>> from astropy.coordinates import Angle
>>> from photutils.aperture import RectangularAnnulus
>>> theta = Angle(80, 'deg')
>>> aper = RectangularAnnulus([10.0, 20.0], 3.0, 8.0, 5.0)
>>> aper = RectangularAnnulus((10.0, 20.0), 3.0, 8.0, 5.0, theta=theta)
>>> pos1 = (10.0, 20.0) # (x, y)
>>> pos2 = (30.0, 40.0)
>>> pos3 = (50.0, 60.0)
>>> aper = RectangularAnnulus([pos1, pos2, pos3], 3.0, 8.0, 5.0)
>>> aper = RectangularAnnulus((pos1, pos2, pos3), 3.0, 8.0, 5.0, theta=theta)
"""
_params = ('positions', 'w_in', 'w_out', 'h_in', 'h_out', 'theta')
positions = PixelPositions('The center pixel position(s).')
w_in = PositiveScalar('The inner full width in pixels.')
w_out = PositiveScalar('The outer full width in pixels.')
h_in = PositiveScalar('The inner full height in pixels.')
h_out = PositiveScalar('The outer full height in pixels.')
theta = ScalarAngleOrValue('The counterclockwise rotation angle as an '
'angular Quantity or value in radians from '
'the positive x axis.')
def __init__(self, positions, w_in, w_out, h_out, h_in=None, theta=0.0):
if not w_out > w_in:
raise ValueError('"w_out" must be greater than "w_in"')
self.positions = positions
self.w_in = w_in
self.w_out = w_out
self.h_out = h_out
if h_in is None:
h_in = self.w_in * self.h_out / self.w_out
else:
if not h_out > h_in:
raise ValueError('"h_out" must be greater than "h_in"')
self.h_in = h_in
self._theta_radians = 0.0 # defined by theta setter
self.theta = theta
@property
def _xy_extents(self):
return self._calc_extents(self.w_out, self.h_out, self._theta_radians)
@property
def area(self):
return self.w_out * self.h_out - self.w_in * self.h_in
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)
inner_xy_positions = self._lower_left_positions(xy_positions,
self.w_in, self.h_in,
self._theta_radians)
outer_xy_positions = self._lower_left_positions(xy_positions,
self.w_out,
self.h_out,
self._theta_radians)
patches = []
theta_deg = self._theta_radians * 180.0 / np.pi
for xy_in, xy_out in zip(inner_xy_positions, outer_xy_positions):
patch_inner = mpatches.Rectangle(xy_in, self.w_in, self.h_in,
angle=theta_deg)
patch_outer = mpatches.Rectangle(xy_out, self.w_out, self.h_out,
angle=theta_deg)
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 RectangularMaskMixin.to_mask(self, method=method,
subpixels=subpixels)
[docs]
def to_sky(self, wcs):
"""
Convert the aperture to a `SkyRectangularAnnulus` 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 : `SkyRectangularAnnulus` object
A `SkyRectangularAnnulus` object.
"""
return SkyRectangularAnnulus(**self._to_sky_params(wcs))
[docs]
class SkyRectangularAperture(SkyAperture):
"""
A rectangular 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.
w : scalar `~astropy.units.Quantity`
The full width of the rectangle in angular units. For
``theta=0`` the width side is along the North-South axis.
h : scalar `~astropy.units.Quantity`
The full height of the rectangle in angular units. For
``theta=0`` the height side is along the East-West axis.
theta : scalar `~astropy.units.Quantity`, optional
The position angle (in angular units) of the rectangle "width"
side. For a right-handed world coordinate system, the position
angle increases counterclockwise from North (PA=0).
Examples
--------
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils.aperture import SkyRectangularAperture
>>> positions = SkyCoord(ra=[10.0, 20.0], dec=[30.0, 40.0], unit='deg')
>>> aper = SkyRectangularAperture(positions, 1.0*u.arcsec, 0.5*u.arcsec)
"""
_params = ('positions', 'w', 'h', 'theta')
positions = SkyCoordPositions('The center position(s) in sky coordinates.')
w = PositiveScalarAngle('The full width in angular units.')
h = PositiveScalarAngle('The full height in angular units.')
theta = ScalarAngle('The position angle (in angular units) of the '
'rectangle "width" side.')
def __init__(self, positions, w, h, theta=0.0 * u.deg):
self.positions = positions
self.w = w
self.h = h
self.theta = theta
[docs]
def to_pixel(self, wcs):
"""
Convert the aperture to a `RectangularAperture` 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 : `RectangularAperture` object
A `RectangularAperture` object.
"""
return RectangularAperture(**self._to_pixel_params(wcs))
[docs]
class SkyRectangularAnnulus(SkyAperture):
r"""
A rectangular 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.
w_in : scalar `~astropy.units.Quantity`
The inner full width of the rectangular annulus in angular
units. For ``theta=0`` the width side is along the North-South
axis.
w_out : scalar `~astropy.units.Quantity`
The outer full width of the rectangular annulus in angular
units. For ``theta=0`` the width side is along the North-South
axis.
h_out : scalar `~astropy.units.Quantity`
The outer full height of the rectangular annulus in angular
units.
h_in : `None` or scalar `~astropy.units.Quantity`
The outer full height of the rectangular annulus in angular
units. If `None`, then the inner full height is calculated as:
.. math:: h_{in} = h_{out}
\left(\frac{w_{in}}{w_{out}}\right)
For ``theta=0`` the height side is along the East-West axis.
theta : scalar `~astropy.units.Quantity`, optional
The position angle (in angular units) of the rectangle "width"
side. For a right-handed world coordinate system, the position
angle increases counterclockwise from North (PA=0).
Examples
--------
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils.aperture import SkyRectangularAnnulus
>>> positions = SkyCoord(ra=[10.0, 20.0], dec=[30.0, 40.0], unit='deg')
>>> aper = SkyRectangularAnnulus(positions, 3.0*u.arcsec, 8.0*u.arcsec,
... 5.0*u.arcsec)
"""
_params = ('positions', 'w_in', 'w_out', 'h_in', 'h_out', 'theta')
positions = SkyCoordPositions('The center position(s) in sky coordinates.')
w_in = PositiveScalarAngle('The inner full width in angular units.')
w_out = PositiveScalarAngle('The outer full width in angular units.')
h_in = PositiveScalarAngle('The inner full height in angular units.')
h_out = PositiveScalarAngle('The outer full height in angular units.')
theta = ScalarAngle('The position angle (in angular units) of the '
'rectangle "width" side.')
def __init__(self, positions, w_in, w_out, h_out, h_in=None,
theta=0.0 * u.deg):
if not w_out > w_in:
raise ValueError('"w_out" must be greater than "w_in".')
self.positions = positions
self.w_in = w_in
self.w_out = w_out
self.h_out = h_out
if h_in is None:
h_in = self.w_in * self.h_out / self.w_out
else:
if not h_out > h_in:
raise ValueError('"h_out" must be greater than "h_in".')
self.h_in = h_in
self.theta = theta
[docs]
def to_pixel(self, wcs):
"""
Convert the aperture to a `RectangularAnnulus` 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 : `RectangularAnnulus` object
A `RectangularAnnulus` object.
"""
return RectangularAnnulus(**self._to_pixel_params(wcs))