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utils.py
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2# LSST Data Management System
3# Copyright 2008, 2009, 2010 LSST Corporation.
4#
5# This product includes software developed by the
6# LSST Project (http://www.lsst.org/).
7#
8# This program is free software: you can redistribute it and/or modify
9# it under the terms of the GNU General Public License as published by
10# the Free Software Foundation, either version 3 of the License, or
11# (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the LSST License Statement and
19# the GNU General Public License along with this program. If not,
20# see <http://www.lsstcorp.org/LegalNotices/>.
21#
22
23__all__ = ["coordFromVec", "makeSkyPolygonFromBBox", "Index2D"]
24
25from typing import NamedTuple
26import numpy
27
28import lsst.sphgeom
29import lsst.geom as geom
30
31_TinyFloat = numpy.finfo(float).tiny
32
33
34def coordFromVec(vec, defRA=None):
35 """Convert an ICRS cartesian vector to an ICRS lsst.geom.SpherePoint
36
37 Parameters
38 ----------
39 vec : `list` of `float`
40 An ICRS catesian vector.
41 defRA : `lsst.geom.Angle` or None
42 The RA to use if the vector is too near a pole;
43 ignored if not near a pole.
44
45 Raises
46 ------
47 RuntimeError
48 If vec too near a pole and defRA is None.
49 """
50 if abs(vec[0]) < _TinyFloat and abs(vec[1]) < _TinyFloat:
51 if defRA is None:
52 raise RuntimeError("At pole and defRA==None")
53 if vec[2] > 0:
54 decDeg = 90.0
55 else:
56 decDeg = -90.0
57 return geom.SpherePoint(defRA, decDeg*geom.degrees)
59
60
61def makeSkyPolygonFromBBox(bbox, wcs):
62 """Make an on-sky polygon from a bbox and a SkyWcs
63
64 Parameters
65 ----------
67 Bounding box of region, in pixel coordinates
69 Celestial WCS
70
71 Returns
72 -------
74 On-sky region
75 """
76 pixelPoints = geom.Box2D(bbox).getCorners()
77 skyPoints = wcs.pixelToSky(pixelPoints)
78 return lsst.sphgeom.ConvexPolygon([sp.getVector() for sp in skyPoints])
79
80
81class Index2D(NamedTuple):
82 """Two dimensional index for patches and cells.
83
84 This class contains the x and y values of the location of a patch
85 within a tract, or a cell within a patch.
86
87 Parameters
88 ----------
89 x : `int`
90 y : `int`
91 """
92 x: int
93 y: int
def coordFromVec(vec, defRA=None)
Definition: utils.py:34