lsst.pipe.tasks.associationUtils Namespace Reference
Functions | |
| toIndex (nside, ra, dec) | |
| toRaDec (nside, index) | |
| eq2xyz (ra, dec) | |
| eq2xyzVec (ra, dec) | |
| convert_spherical (ra, dec) | |
| convert_spherical_array (array) | |
| query_disc (nside, ra, dec, max_rad, min_rad=0) | |
| obj_id_to_ss_object_id (objID) | |
| ss_object_id_to_obj_id (ssObjectID) | |
Detailed Description
Utilities for interfacing with hpgeom. Originally implemented in http://github.com/LSSTDESC/dia_pipe and then translated to hpgeom.
Function Documentation
◆ convert_spherical()
| lsst.pipe.tasks.associationUtils.convert_spherical | ( | ra, | |
| dec ) |
Convert from ra,dec to spherical coordinates.
Used in query_disc.
Parameters
----------
ra : `float`
RA in radians.
dec : `float`
Declination in radians
Definition at line 124 of file associationUtils.py.
124def convert_spherical(ra, dec):
125 """Convert from ra,dec to spherical coordinates.
126
127 Used in query_disc.
128
129 Parameters
130 ----------
131 ra : `float`
132 RA in radians.
133 dec : `float`
134 Declination in radians
135 """
136 return np.dstack([np.cos(dec*np.pi/180)*np.cos(ra*np.pi/180),
137 np.cos(dec*np.pi/180)*np.sin(ra*np.pi/180),
138 np.sin(dec*np.pi/180)])[0]
139
140
◆ convert_spherical_array()
| lsst.pipe.tasks.associationUtils.convert_spherical_array | ( | array | ) |
Convert from and a array ra,dec to spherical coordinates.
Used in query_disc
Parameters
----------
array : `numpy.ndarray`, (N, 2)
(N, 2) Array of RA, DEC values.
Returns
-------
vecs : `numpy.ndarray`, (N, 3)
Vectors on the unit sphere
Definition at line 141 of file associationUtils.py.
141def convert_spherical_array(array):
142 """Convert from and a array ra,dec to spherical coordinates.
143
144 Used in query_disc
145
146 Parameters
147 ----------
148 array : `numpy.ndarray`, (N, 2)
149 (N, 2) Array of RA, DEC values.
150
151 Returns
152 -------
153 vecs : `numpy.ndarray`, (N, 3)
154 Vectors on the unit sphere
155 """
156 ra = array[:, 0]
157 dec = array[:, 1]
158 return convert_spherical(ra, dec)
159
160
◆ eq2xyz()
| lsst.pipe.tasks.associationUtils.eq2xyz | ( | ra, | |
| dec ) |
Convert from equatorial ra,dec in degrees to x,y,z on unit sphere.
Parameters
----------
ra : `float`
RA in degrees.
dec : `float`
Declination in degrees
Returns
-------
xyz : `numpy.ndarray`, (3,)
Float xyz positions on the unit sphere.
Definition at line 72 of file associationUtils.py.
72def eq2xyz(ra, dec):
73 """Convert from equatorial ra,dec in degrees to x,y,z on unit sphere.
74
75 Parameters
76 ----------
77 ra : `float`
78 RA in degrees.
79 dec : `float`
80 Declination in degrees
81
82 Returns
83 -------
84 xyz : `numpy.ndarray`, (3,)
85 Float xyz positions on the unit sphere.
86 """
87 phi = np.deg2rad(ra)
88 theta = np.pi/2 - np.deg2rad(dec)
89 sintheta = np.sin(theta)
90 x = sintheta*np.cos(phi)
91 y = sintheta*np.sin(phi)
92 z = np.cos(theta)
93 return np.array([x, y, z])
94
95
◆ eq2xyzVec()
| lsst.pipe.tasks.associationUtils.eq2xyzVec | ( | ra, | |
| dec ) |
Convert equatorial ra,dec in degrees to x,y,z on the unit sphere
parameters
Vectorized version of ``eq2xyz``
Parameters
----------
ra : array_like, (N,)
Array of RA in degrees.
dec : array_like, (N,)
Declination in degrees
Returns
-------
vec : `numpy.ndarray`, (N,3)
Array of unitsphere 3-vectors.
Definition at line 96 of file associationUtils.py.
96def eq2xyzVec(ra, dec):
97 """Convert equatorial ra,dec in degrees to x,y,z on the unit sphere
98 parameters
99
100 Vectorized version of ``eq2xyz``
101
102 Parameters
103 ----------
104 ra : array_like, (N,)
105 Array of RA in degrees.
106 dec : array_like, (N,)
107 Declination in degrees
108
109 Returns
110 -------
111 vec : `numpy.ndarray`, (N,3)
112 Array of unitsphere 3-vectors.
113 """
114 ra = np.array(ra, dtype='f8', ndmin=1, copy=False)
115 dec = np.array(dec, dtype='f8', ndmin=1, copy=False)
116 if ra.size != dec.size:
117 raise ValueError("ra,dec not same size: %s,%s" % (ra.size, dec.size))
118
119 vec = eq2xyz(ra, dec)
120
121 return vec
122
123
◆ obj_id_to_ss_object_id()
| lsst.pipe.tasks.associationUtils.obj_id_to_ss_object_id | ( | objID | ) |
Convert from Minor Planet Center packed provisional object ID to
Rubin ssObjectID.
Parameters
----------
objID : `str`
Minor Planet Center packed provisional designation for a small solar
system object. Must be fewer than eight characters.
Returns
-------
ssObjectID : `int`
Rubin ssObjectID
Raises
------
ValueError
Raised if either objID is shorter than 7 or longer than 8 characters or contains
illegal objID characters
Definition at line 198 of file associationUtils.py.
198def obj_id_to_ss_object_id(objID):
199 """Convert from Minor Planet Center packed provisional object ID to
200 Rubin ssObjectID.
201
202 Parameters
203 ----------
204 objID : `str`
205 Minor Planet Center packed provisional designation for a small solar
206 system object. Must be fewer than eight characters.
207
208 Returns
209 -------
210 ssObjectID : `int`
211 Rubin ssObjectID
212
213 Raises
214 ------
215 ValueError
216 Raised if either objID is shorter than 7 or longer than 8 characters or contains
217 illegal objID characters
218 """
219 if len(objID) > 8:
220 raise ValueError(f'objID longer than 8 characters: "{objID}"')
221 if len(objID) < 7:
222 raise ValueError(f'objID shorter than 7 characters: "{objID}"')
223 if any([ord(c) > 255 for c in objID]):
224 raise ValueError(f'{[c for c in objID if ord(c) > 255]} not legal objID characters (ascii [1, 255])')
225
226 ssObjectID = ord(objID[0])
227 for character in objID[1:]:
228 ssObjectID <<= 8
229 ssObjectID += ord(character)
230 return ssObjectID
231
232
◆ query_disc()
| lsst.pipe.tasks.associationUtils.query_disc | ( | nside, | |
| ra, | |||
| dec, | |||
| max_rad, | |||
| min_rad = 0 ) |
Get the list of healpix indices within max_rad, min_rad given in radians
around ra,dec given in degrees
Parameters
----------
nside : `int`
Resolution of the healpixels to search/return.
ra : `float`
RA in degrees.
dec : `float`
Declination in degrees
max_rad : `float`
Max distance in radians to search nearby healpixels.
min_rad : `float`, optional
Minimum distance in radians to search healpixels. Default = 0.
Definition at line 161 of file associationUtils.py.
161def query_disc(nside, ra, dec, max_rad, min_rad=0):
162 """Get the list of healpix indices within max_rad, min_rad given in radians
163 around ra,dec given in degrees
164
165 Parameters
166 ----------
167 nside : `int`
168 Resolution of the healpixels to search/return.
169 ra : `float`
170 RA in degrees.
171 dec : `float`
172 Declination in degrees
173 max_rad : `float`
174 Max distance in radians to search nearby healpixels.
175 min_rad : `float`, optional
176 Minimum distance in radians to search healpixels. Default = 0.
177 """
178 ra = np.atleast_1d(ra)
179 dec = np.atleast_1d(dec)
180
181 max_rad_deg = np.rad2deg(max_rad)
182
183 pixels = np.unique(
184 [hpg.query_circle(nside, a, b, max_rad_deg, nest=False)
185 for (a, b) in zip(ra, dec)])
186
187 if min_rad > 0 and len(pixels) > 0:
188 vec0 = convert_spherical(ra, dec)
189 min_rad2 = min_rad**2
190 vecs = convert_spherical_array(toRaDec(nside, pixels))
191 dsq = np.sum((vecs - vec0)**2, axis=1)
192 match = dsq > min_rad2
193 pixels = pixels[match]
194
195 return pixels
196
197
◆ ss_object_id_to_obj_id()
| lsst.pipe.tasks.associationUtils.ss_object_id_to_obj_id | ( | ssObjectID | ) |
Convert from Rubin ssObjectID to Minor Planet Center packed provisional
object ID.
Parameters
----------
ssObjectID : `int`
Rubin ssObjectID
Returns
-------
objID : `str`
Minor Planet Center packed provisional designation.
Raises
------
Definition at line 233 of file associationUtils.py.
233def ss_object_id_to_obj_id(ssObjectID):
234 """Convert from Rubin ssObjectID to Minor Planet Center packed provisional
235 object ID.
236
237 Parameters
238 ----------
239 ssObjectID : `int`
240 Rubin ssObjectID
241
242 Returns
243 -------
244 objID : `str`
245 Minor Planet Center packed provisional designation.
246
247 Raises
248 ------
249 """
250 if ssObjectID < 0 or ssObjectID >= (1 << 64):
251 raise ValueError(f'ssObjectID ({ssObjectID}) outside [0, 2^64 - 1].')
252
253 objID = ''.join([chr((ssObjectID >> (8 * i)) % 256) for i in reversed(range(0, 8))])
254 objID = objID.replace('\x00', '')
255 return objID
◆ toIndex()
| lsst.pipe.tasks.associationUtils.toIndex | ( | nside, | |
| ra, | |||
| dec ) |
Return healpix index given ra, dec in degrees
Parameters
----------
nside : `int`
Power of 2 nside healpix resolution.
ra : `float`
RA in degrees.
dec : `float`
Declination in degrees
Returns
-------
index : `int`
Unique healpix pixel ID containing point RA, DEC at resolution nside.
Definition at line 33 of file associationUtils.py.
33def toIndex(nside, ra, dec):
34 """Return healpix index given ra, dec in degrees
35
36 Parameters
37 ----------
38 nside : `int`
39 Power of 2 nside healpix resolution.
40 ra : `float`
41 RA in degrees.
42 dec : `float`
43 Declination in degrees
44
45 Returns
46 -------
47 index : `int`
48 Unique healpix pixel ID containing point RA, DEC at resolution nside.
49 """
50 return hpg.angle_to_pixel(nside, ra, dec, nest=False)
51
52
◆ toRaDec()
| lsst.pipe.tasks.associationUtils.toRaDec | ( | nside, | |
| index ) |
Convert from healpix index to ra,dec in degrees
Parameters
----------
nside : `int`
Resolution of healpixel "grid".
index : `int`
Index of the healpix pixel we want to find the location of.
Returns
-------
pos : `numpy.ndarray`, (2,)
RA and DEC of healpix pixel location in degrees.
Definition at line 53 of file associationUtils.py.
53def toRaDec(nside, index):
54 """Convert from healpix index to ra,dec in degrees
55
56 Parameters
57 ----------
58 nside : `int`
59 Resolution of healpixel "grid".
60 index : `int`
61 Index of the healpix pixel we want to find the location of.
62
63 Returns
64 -------
65 pos : `numpy.ndarray`, (2,)
66 RA and DEC of healpix pixel location in degrees.
67 """
68 ra, dec = hpg.pixel_to_angle(nside, index, nest=False)
69 return np.dstack((ra, dec))[0]
70
71
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