/usr/lib/python3/dist-packages/pymoc/util/catalog.py is in python3-pymoc 0.4.2-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | # Copyright (C) 2015 East Asian Observatory.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from __future__ import absolute_import
from math import pi
from astropy.coordinates import SkyCoord
from astropy.io import ascii
from astropy.units import arcsecond, hour, degree
from astropy.units.quantity import Quantity
from healpy.pixelfunc import ang2pix, get_all_neighbours, pix2ang
import numpy as np
from ..moc import MOC
def catalog_to_moc(catalog, radius, order):
"""
Convert a catalog to a MOC.
The catalog is given as an Astropy SkyCoord object containing
multiple coordinates. The radius of catalog entries can be
given as an Astropy Quantity (with units), otherwise it is assumed
to be in arcseconds.
Note: this function uses a simple flood-filling approach and is
very slow, especially when used with a large radius for catalog objects
or a high resolution order.
"""
if not isinstance(radius, Quantity):
radius = radius * arcsecond
nside = 2 ** order
# Ensure catalog is in ICRS coordinates.
catalog = catalog.icrs
# Determine central cell for each catalog entry.
phi = catalog.ra.radian
theta = (pi / 2) - catalog.dec.radian
cells = np.unique(ang2pix(nside, theta, phi, nest=True))
# Iteratively consider the neighbors of cells within our
# catalog regions.
new_cells = cells
rejected = np.array((), dtype=np.int64)
while True:
# Find new valid neighboring cells which we didn't already
# consider.
neighbors = np.unique(np.ravel(
get_all_neighbours(nside, new_cells, nest=True)))
neighbors = np.extract(
[(x != -1) and (x not in cells) and (x not in rejected)
for x in neighbors], neighbors)
# Get the coordinates of each of these neighbors and compare them
# to the catalog entries.
(theta, phi) = pix2ang(nside, neighbors, nest=True)
coords = SkyCoord(phi, (pi / 2) - theta, frame='icrs', unit='rad')
(idx, sep2d, dist3d) = coords.match_to_catalog_sky(catalog)
within_range = (sep2d < radius)
# If we didn't find any new cells within range,
# end the iterative process.
if not np.any(within_range):
break
new_cells = neighbors[within_range]
cells = np.concatenate((cells, new_cells))
rejected = np.concatenate((
rejected, neighbors[np.logical_not(within_range)]))
# Create new MOC object using our collection of cells.
return MOC(order=order, cells=cells, moctype='CATALOG')
def read_ascii_catalog(filename, format_, unit=None):
"""
Read an ASCII catalog file using Astropy.
This routine is used by pymoctool to load coordinates from a
catalog file in order to generate a MOC representation.
"""
catalog = ascii.read(filename, format=format_)
columns = catalog.columns
if 'RA' in columns and 'Dec' in columns:
if unit is None:
unit = (hour, degree)
coords = SkyCoord(catalog['RA'],
catalog['Dec'],
unit=unit,
frame='icrs')
elif 'Lat' in columns and 'Lon' in columns:
if unit is None:
unit = (degree, degree)
coords = SkyCoord(catalog['Lon'],
catalog['Lat'],
unit=unit,
frame='galactic')
else:
raise Exception('columns RA,Dec or Lon,Lat not found')
return coords
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