"""
Example script illustrating compound regions.
"""
import numpy as np
import matplotlib.pyplot as plt
from astropy.coordinates import SkyCoord, Angle
from regions import CircleSkyRegion, make_example_dataset
# load example dataset to get skymap
config = dict(crval=(0, 0),
crpix=(180, 90),
cdelt=(-1, 1),
shape=(180, 360))
dataset = make_example_dataset(data='simulated', config=config)
wcs = dataset.wcs
# remove sources
dataset.image.data = np.zeros_like(dataset.image.data)
# define 2 sky circles
circle1 = CircleSkyRegion(
center=SkyCoord(20, 0, unit='deg', frame='galactic'),
radius=Angle('30 deg')
)
circle2 = CircleSkyRegion(
center=SkyCoord(50, 45, unit='deg', frame='galactic'),
radius=Angle('30 deg'),
)
"""Example how to plot sky regions on a sky image.
"""
from astropy.coordinates import SkyCoord, Angle
from regions import (
make_example_dataset,
CircleSkyRegion,
)
import matplotlib.pyplot as plt
config = dict(crpix=(18, 9), cdelt=(-10, 10), shape=(18, 36))
dataset = make_example_dataset(data='simulated', config=config)
wcs = dataset.wcs
fig = plt.figure()
ax = fig.add_axes([0.15, 0.1, 0.8, 0.8], projection=wcs)
ax.set_xlim(-0.5, dataset.config['shape'][1] - 0.5)
ax.set_ylim(-0.5, dataset.config['shape'][0] - 0.5)
ax.imshow(dataset.image.data, cmap='gray', vmin=0, vmax=1,
interpolation='nearest', origin='lower')
for source in dataset.source_table:
# Plot a sky circle around each source
center = SkyCoord(source['GLON'], source['GLAT'], unit='deg', frame='galactic')
radius = Angle(20, 'deg')
region = CircleSkyRegion(center=center, radius=radius)
pix_region = region.to_pixel(wcs=wcs)
pix_region.plot(ax=ax, edgecolor='yellow', facecolor='yellow', alpha=0.5, lw=3)