CircleAnnulusPixelRegion

class regions.CircleAnnulusPixelRegion(center, inner_radius, outer_radius, meta=None, visual=None)

Bases: AnnulusPixelRegion

A circular annulus in pixel coordinates.

Parameters:

centerPixCoord

The position of the center of the annulus.

inner_radiusfloat

The inner radius of the annulus in pixels.

outer_radiusfloat

The outer radius of the annulus in pixels.

metaRegionMeta or dict, optional

A dictionary that stores the meta attributes of the region.

visualRegionVisual or dict, optional

A dictionary that stores the visual meta attributes of the region.

Examples

import matplotlib.pyplot as plt
from regions import CircleAnnulusPixelRegion, PixCoord

fig, ax = plt.subplots()

reg = CircleAnnulusPixelRegion(PixCoord(x=6, y=6),
                               inner_radius=5.5,
                               outer_radius=8.0)
patch = reg.plot(ax=ax, facecolor='none', edgecolor='red', lw=2,
                 label='Circle Annulus')

ax.legend(handles=(patch,), loc='upper center')
ax.set_xlim(-5, 20)
ax.set_ylim(-5, 20)
ax.set_aspect('equal')

(Source code, png, hires.png, pdf, svg)

Attributes Summary

center	The center pixel position as a PixCoord.
inner_radius	The inner radius in pixels as a float.
meta	The meta attributes as a RegionMeta
outer_radius	The outer radius in pixels as a float.
visual	The visual attributes as a RegionVisual.

Methods Summary

to_polygon(*[, n_vertices])	Return a CompoundPixelRegion of two PolygonPixelRegion objects that approximates this annulus.
to_sky(wcs, *[, as_ellipse])	Return a sky region from this pixel region.
to_spherical_sky(wcs, *[, ...])	Convert to an equivalent spherical SphericalSkyRegion instance.

Attributes Documentation

center

The center pixel position as a PixCoord.

inner_radius

The inner radius in pixels as a float.

meta

The meta attributes as a RegionMeta

outer_radius

The outer radius in pixels as a float.

visual

The visual attributes as a RegionVisual.

Methods Documentation

to_polygon(*, n_vertices=100)

Return a CompoundPixelRegion of two PolygonPixelRegion objects that approximates this annulus.

Parameters:

n_verticesint, optional

The number of polygon vertices for each circle. Default is 100.

Returns:

polygonCompoundPixelRegion

A compound region of two polygon regions approximating the annulus.

to_sky(wcs, *, as_ellipse=False)

Return a sky region from this pixel region.

Parameters:

wcsWCS object

A world coordinate system (WCS) transformation that supports the astropy shared interface for WCS (e.g., astropy.wcs.WCS).

as_ellipsebool, optional

If True, return an EllipseAnnulusSkyRegion instead of a CircleAnnulusSkyRegion. An ellipse annulus is generally a better approximation when the WCS has distortions or different pixel scales along different axes. Default is False.

Returns:

regionCircleAnnulusSkyRegion or EllipseAnnulusSkyRegion

The sky region. An ellipse annulus is returned if as_ellipse is True.

to_spherical_sky(wcs, *, boundary_distortions=False, n_vertices=None)

Convert to an equivalent spherical SphericalSkyRegion instance.

Parameters:

wcsWCS instance

The world coordinate system transformation to use to convert between pixel and sky coordinates.

boundary_distortionsbool, optional

If True, the projection-induced distortions of the region’s boundary are preserved by discretizing the boundary into a polygon and transforming that polygon. If False (default), the region is converted to an equivalent idealized shape that ignores these boundary distortions.

n_verticesint, optional

The number of polygon vertices for boundary discretization. This keyword will have no effect unless boundary_distortions=True. Default is 100.

Returns:

spherical_sky_regionSphericalSkyRegion

A spherical sky region, with an equivalent shape (if boundary_distortions is False), or a discretized polygon of the boundary (if boundary_distortions is True).