TextPixelRegion

class regions.TextPixelRegion(center, text, meta=None, visual=None)

Bases: PointPixelRegion

A text string in pixel coordinates.

Parameters:

centerPixCoord

The leftmost point of the text string before rotation.

textstr

The text string.

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 PixCoord, RegionVisual, TextPixelRegion

fig, ax = plt.subplots()

center = PixCoord(x=15, y=10)
visual = RegionVisual({'textangle': 30})
reg = TextPixelRegion(center=center, text='Hello World!',
                      visual=visual)
reg.plot(ax=ax)

ax.set_xlim(10, 30)
ax.set_ylim(2.5, 20)
ax.set_aspect('equal')

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

Attributes Summary

center	The leftmost pixel position (before rotation) as a PixCoord.
meta	The meta attributes as a RegionMeta
visual	The visual attributes as a RegionVisual.

Methods Summary

as_artist([origin])	Return a matplotlib Text object for this region (matplotlib.text.Text).
to_sky(wcs)	Return a region defined in sky coordinates.
to_spherical_sky(wcs, *[, ...])	Convert to an equivalent spherical SphericalSkyRegion instance.

Attributes Documentation

center

The leftmost pixel position (before rotation) as a PixCoord.

meta

The meta attributes as a RegionMeta

visual

The visual attributes as a RegionVisual.

Methods Documentation

as_artist(origin=(0, 0), **kwargs)

Return a matplotlib Text object for this region (matplotlib.text.Text).

Parameters:

originarray_like, optional

The (x, y) pixel position of the origin of the displayed image.

**kwargsdict

Any keyword arguments accepted by Text. These keywords will override any visual meta attributes of this region.

Returns:

artistText

A matplotlib Text object.

to_sky(wcs)

Return a region defined in sky coordinates.

Parameters:

wcsWCS

The world coordinate system transformation to use to convert from pixels to sky coordinates.

Returns:

sky_regionSkyRegion

The sky region.

Notes

The conversion between pixel and sky coordinates is an approximation. The pixel region shape is mapped to a sky region shape using the local pixel scale and angle at the region center. Projection effects over the extent of the region are not accounted for. The region shape type is always preserved (e.g., a CirclePixelRegion converts to a CircleSkyRegion).

For WCS with distortions (e.g., SIP), the local Jacobian matrix of the WCS transformation is used to compute directional scale factors and angle. For WCS without distortions, a local pixel scale and angle are computed using offset-based methods.

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).