def from_polygon(cls, lon, lat, max_depth=10):
"""
Creates a MOC from a polygon
The polygon is given as lon and lat `astropy.units.Quantity` that define the
vertices of the polygon. Concave, convex and self-intersecting polygons are accepted.
Parameters
----------
lon : `astropy.units.Quantity`
The longitudes defining the polygon. Can describe convex and
concave polygons but not self-intersecting ones.
lat : `astropy.units.Quantity`
The latitudes defining the polygon. Can describe convex and concave
polygons but not self-intersecting ones.
max_depth : int, optional
The resolution of the MOC. Set to 10 by default.
Returns
-------
result : `~mocpy.moc.MOC`
The resulting MOC
"""
pix, depth, fully_covered_flags = cdshealpix.polygon_search(lon, lat, max_depth)
return MOC.from_healpix_cells(pix, depth, fully_covered_flags)
from cdshealpix import polygon_search
import astropy.units as u
import numpy as np
lon = [20, -20, -20, 20] * u.deg
lat = [20, 20, -20, -20] * u.deg
depth = 7
ipix, depth, fully_covered = polygon_search(lon, lat, depth)
from mocpy import MOC, WCS
from astropy.coordinates import SkyCoord, Angle
moc = MOC.from_healpix_cells(ipix, depth, fully_covered)
# Plot the MOC using matplotlib
import matplotlib.pyplot as plt
fig = plt.figure(111, figsize=(10, 10))
# Define a astropy WCS easily
with WCS(fig,
fov=100 * u.deg,
center=SkyCoord(0, 0, unit='deg', frame='icrs'),
coordsys="icrs",
rotation=Angle(0, u.degree),
projection="AIT") as wcs:
ax = fig.add_subplot(1, 1, 1, projection=wcs)
# Call fill with a matplotlib axe and the `~astropy.wcs.WCS` wcs object.
moc.fill(ax=ax, wcs=wcs, alpha=0.5, fill=True, color="green")
# Draw the perimeter of the MOC in black
moc.border(ax=ax, wcs=wcs, alpha=0.5, color="black")
plt.xlabel('ra')
plt.ylabel('dec')