# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This module defines elliptical regions in both pixel and sky coordinates.
"""
import math
import astropy.units as u
import numpy as np
from astropy.coordinates import Angle
from regions._geometry import elliptical_overlap_grid
from regions._utils.wcs_helpers import pixel_scale_angle_at_skycoord
from regions.core.attributes import (PositiveScalar, PositiveScalarAngle,
RegionMetaDescr, RegionVisualDescr,
ScalarAngle, ScalarPixCoord,
ScalarSkyCoord)
from regions.core.bounding_box import RegionBoundingBox
from regions.core.core import PixelRegion, SkyRegion
from regions.core.mask import RegionMask
from regions.core.metadata import RegionMeta, RegionVisual
from regions.core.pixcoord import PixCoord
__all__ = ['EllipsePixelRegion', 'EllipseSkyRegion']
[docs]
class EllipsePixelRegion(PixelRegion):
"""
An ellipse in pixel coordinates.
Parameters
----------
center : `~regions.PixCoord`
The position of the center of the ellipse.
width : float
The width of the ellipse (before rotation) in pixels
height : float
The height of the ellipse (before rotation) in pixels
angle : `~astropy.units.Quantity`, optional
The rotation angle of the ellipse, measured anti-clockwise. If
set to zero (the default), the width axis is lined up with the x
axis.
meta : `~regions.RegionMeta` or `dict`, optional
A dictionary that stores the meta attributes of the region.
visual : `~regions.RegionVisual` or `dict`, optional
A dictionary that stores the visual meta attributes of the
region.
Examples
--------
.. plot::
:include-source:
from astropy.coordinates import Angle
from regions import PixCoord, EllipsePixelRegion
import matplotlib.pyplot as plt
fig, ax = plt.subplots(1, 1)
reg = EllipsePixelRegion(PixCoord(15, 10), width=16, height=10,
angle=Angle(30, 'deg'))
patch = reg.plot(ax=ax, facecolor='none', edgecolor='red', lw=2,
label='Ellipse')
ax.legend(handles=(patch,), loc='upper center')
ax.set_xlim(0, 30)
ax.set_ylim(0, 20)
ax.set_aspect('equal')
"""
_params = ('center', 'width', 'height', 'angle')
_mpl_artist = 'Patch'
center = ScalarPixCoord('The center pixel position as a |PixCoord|.')
width = PositiveScalar('The width of the ellipse (before rotation) in '
'pixels as a float.')
height = PositiveScalar('The height of the ellipse (before rotation) in '
'pixels as a float.')
angle = ScalarAngle('The rotation angle measured anti-clockwise as a '
'|Quantity| angle.')
meta = RegionMetaDescr('The meta attributes as a |RegionMeta|')
visual = RegionVisualDescr('The visual attributes as a |RegionVisual|.')
def __init__(self, center, width, height, angle=0. * u.deg, meta=None,
visual=None):
self.center = center
self.width = width
self.height = height
self.angle = angle
self.meta = meta or RegionMeta()
self.visual = visual or RegionVisual()
@property
def area(self):
return math.pi / 4 * self.width * self.height
[docs]
def contains(self, pixcoord):
pixcoord = PixCoord._validate(pixcoord, name='pixcoord')
cos_angle = np.cos(self.angle)
sin_angle = np.sin(self.angle)
dx = pixcoord.x - self.center.x
dy = pixcoord.y - self.center.y
in_ell = ((2 * (cos_angle * dx + sin_angle * dy) / self.width) ** 2
+ (2 * (sin_angle * dx - cos_angle * dy)
/ self.height) ** 2 <= 1.)
if self.meta.get('include', True):
return in_ell
else:
return np.logical_not(in_ell)
[docs]
def to_sky(self, wcs):
center = wcs.pixel_to_world(self.center.x, self.center.y)
_, pixscale, north_angle = pixel_scale_angle_at_skycoord(center, wcs)
height = Angle(self.height * u.pix * pixscale, 'arcsec')
width = Angle(self.width * u.pix * pixscale, 'arcsec')
# region sky angles are defined relative to the WCS longitude axis;
# photutils aperture sky angles are defined as the PA of the
# semimajor axis (i.e., relative to the WCS latitude axis)
angle = self.angle - (north_angle - 90 * u.deg)
return EllipseSkyRegion(center, width, height, angle=angle,
meta=self.meta.copy(),
visual=self.visual.copy())
@property
def bounding_box(self):
"""
The minimal bounding box (`~regions.RegionBoundingBox`)
enclosing the exact elliptical region.
"""
# We use the solution described in
# https://stackoverflow.com/a/14163413
cos_theta = np.cos(self.angle)
sin_theta = np.sin(self.angle)
width_x = 0.5 * self.width * cos_theta
width_y = 0.5 * self.width * sin_theta
height_x = 0.5 * self.height * -sin_theta
height_y = 0.5 * self.height * cos_theta
dx = np.sqrt(width_x**2 + height_x**2)
dy = np.sqrt(width_y**2 + height_y**2)
xmin = self.center.x - dx
xmax = self.center.x + dx
ymin = self.center.y - dy
ymax = self.center.y + dy
return RegionBoundingBox.from_float(xmin, xmax, ymin, ymax)
[docs]
def to_mask(self, mode='center', subpixels=5):
# NOTE: assumes this class represents a single circle
self._validate_mode(mode, subpixels)
if mode == 'center':
mode = 'subpixels'
subpixels = 1
# Find bounding box and mask size
bbox = self.bounding_box
ny, nx = bbox.shape
# Find position of pixel edges and recenter so that ellipse is
# at origin
xmin = float(bbox.ixmin) - 0.5 - self.center.x
xmax = float(bbox.ixmax) - 0.5 - self.center.x
ymin = float(bbox.iymin) - 0.5 - self.center.y
ymax = float(bbox.iymax) - 0.5 - self.center.y
if mode == 'subpixels':
use_exact = 0
else:
use_exact = 1
fraction = elliptical_overlap_grid(xmin, xmax, ymin, ymax, nx, ny,
0.5 * self.width, 0.5 * self.height,
self.angle.to(u.rad).value,
use_exact, subpixels)
return RegionMask(fraction, bbox=bbox)
[docs]
def as_artist(self, origin=(0, 0), **kwargs):
"""
Return a matplotlib patch object for the region
(`matplotlib.patches.Ellipse`).
Parameters
----------
origin : array_like, optional
The ``(x, y)`` pixel position of the origin of the displayed
image.
**kwargs : dict
Any keyword arguments accepted by
`~matplotlib.patches.Ellipse`. These keywords will override
any visual meta attributes of this region.
Returns
-------
artist : `~matplotlib.patches.Ellipse`
A matplotlib ellipse patch.
"""
from matplotlib.patches import Ellipse
xy = self.center.x - origin[0], self.center.y - origin[1]
width = self.width
height = self.height
# matplotlib expects rotation in degrees (anti-clockwise)
angle = self.angle.to('deg').value
mpl_kwargs = self.visual.define_mpl_kwargs(self._mpl_artist)
mpl_kwargs.update(kwargs)
return Ellipse(xy=xy, width=width, height=height, angle=angle,
**mpl_kwargs)
def _update_from_mpl_selector(self, *args, **kwargs):
xmin, xmax, ymin, ymax = self._mpl_selector.extents
self.center = PixCoord(x=0.5 * (xmin + xmax),
y=0.5 * (ymin + ymax))
self.width = (xmax - xmin)
self.height = (ymax - ymin)
self.angle = 0. * u.deg
if self._mpl_selector_callback is not None:
self._mpl_selector_callback(self)
[docs]
def as_mpl_selector(self, ax, active=True, sync=True, callback=None,
**kwargs):
"""
A matplotlib editable widget for this region
(`matplotlib.widgets.EllipseSelector`).
Parameters
----------
ax : `~matplotlib.axes.Axes`
The matplotlib axes to add the selector to.
active : bool, optional
Whether the selector should be active by default.
sync : bool, optional
If `True` (the default), the region will be kept in
sync with the selector. Otherwise, the selector will be
initialized with the values from the region but the two will
then be disconnected.
callback : callable, optional
If specified, this function will be called every time the
region is updated. This only has an effect if ``sync`` is
`True`. If a callback is set, it is called for the first
time once the selector has been created.
drag_from_anywhere : bool, optional
If `True`, the selector can be moved by clicking anywhere within
its bounds, else only at the central anchor
(only available with matplotlib 3.5 upwards; default: `False`).
**kwargs : dict
Additional keyword arguments that are passed to
`matplotlib.widgets.EllipseSelector`.
Returns
-------
selector : `matplotlib.widgets.EllipseSelector`
The matplotlib selector.
Notes
-----
Once a selector has been created, you will need to keep a
reference to it until you no longer need it. In addition,
you can enable/disable the selector at any point by calling
``selector.set_active(True)`` or ``selector.set_active(False)``.
"""
from matplotlib.widgets import EllipseSelector
from regions._utils.optional_deps import MPL_VERSION
if hasattr(self, '_mpl_selector'):
raise AttributeError('Cannot attach more than one selector to a region.')
if self.angle.value != 0:
raise NotImplementedError('Cannot create matplotlib selector for rotated ellipse.')
if sync:
sync_callback = self._update_from_mpl_selector
else:
def sync_callback(*args, **kwargs):
pass
rectprops = {'edgecolor': self.visual.get('color', 'black'),
'facecolor': 'none',
'linewidth': self.visual.get('linewidth', 1),
'linestyle': self.visual.get('linestyle', 'solid')}
rectprops.update(kwargs.pop('props', dict()))
# `rectprops` renamed `props` in mpl 3.5 and deprecated for 3.7.
if MPL_VERSION < 35:
kwargs.update({'rectprops': rectprops})
else:
kwargs.update({'props': rectprops})
self._mpl_selector = EllipseSelector(ax, sync_callback, interactive=True, **kwargs)
self._mpl_selector.extents = (self.center.x - self.width / 2,
self.center.x + self.width / 2,
self.center.y - self.height / 2,
self.center.y + self.height / 2)
self._mpl_selector.set_active(active)
self._mpl_selector_callback = callback
if sync and self._mpl_selector_callback is not None:
self._mpl_selector_callback(self)
return self._mpl_selector
[docs]
def rotate(self, center, angle):
"""
Rotate the region.
Positive ``angle`` corresponds to counter-clockwise rotation.
Parameters
----------
center : `~regions.PixCoord`
The rotation center point.
angle : `~astropy.coordinates.Angle`
The rotation angle.
Returns
-------
region : `EllipsePixelRegion`
The rotated region (which is an independent copy).
"""
center = self.center.rotate(center, angle)
angle = self.angle + angle
return self.copy(center=center, angle=angle)
[docs]
class EllipseSkyRegion(SkyRegion):
"""
An ellipse defined using sky coordinates.
Parameters
----------
center : `~astropy.coordinates.SkyCoord`
The position of the center of the ellipse.
width : `~astropy.units.Quantity`
The width of the ellipse (before rotation) as an angle.
height : `~astropy.units.Quantity`
The height of the ellipse (before rotation) as an angle.
angle : `~astropy.units.Quantity`, optional
The rotation angle of the ellipse, measured anti-clockwise. If
set to zero (the default), the width axis is lined up with the
longitude axis of the celestial coordinates.
meta : `~regions.RegionMeta` or `dict`, optional
A dictionary that stores the meta attributes of the region.
visual : `~regions.RegionVisual` or `dict`, optional
A dictionary that stores the visual meta attributes of the
region.
"""
_params = ('center', 'width', 'height', 'angle')
center = ScalarSkyCoord('The center position as a |SkyCoord|.')
width = PositiveScalarAngle('The width of the ellipse (before rotation) '
'as a |Quantity| angle.')
height = PositiveScalarAngle('The height of the ellipse (before rotation) '
'as a |Quantity| angle.')
angle = ScalarAngle('The rotation angle measured anti-clockwise as a '
'|Quantity| angle.')
meta = RegionMetaDescr('The meta attributes as a |RegionMeta|')
visual = RegionVisualDescr('The visual attributes as a |RegionVisual|.')
def __init__(self, center, width, height, angle=0. * u.deg, meta=None,
visual=None):
self.center = center
self.width = width
self.height = height
self.angle = angle
self.meta = meta or RegionMeta()
self.visual = visual or RegionVisual()
[docs]
def to_pixel(self, wcs):
center, pixscale, north_angle = pixel_scale_angle_at_skycoord(
self.center, wcs)
height = (self.height / pixscale).to(u.pixel).value
width = (self.width / pixscale).to(u.pixel).value
# region sky angles are defined relative to the WCS longitude axis;
# photutils aperture sky angles are defined as the PA of the
# semimajor axis (i.e., relative to the WCS latitude axis)
angle = self.angle + (north_angle - 90 * u.deg)
return EllipsePixelRegion(center, width, height, angle=angle,
meta=self.meta.copy(),
visual=self.visual.copy())