Coverage for python / lsst / images / tests / _creation.py: 73%

1# This file is part of lsst-images. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (https://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# Use of this source code is governed by a 3-clause BSD-style 

10# license that can be found in the LICENSE file. 

11 

12from __future__ import annotations 

13 

14__all__ = ("make_random_projection",) 

15 

16 

17import astropy.units as u 

18import astropy.wcs.wcsapi 

19import numpy as np 

20 

21from .._geom import Box 

22from .._transforms import Frame, Projection 

23 

24 

25def make_random_projection[F: Frame](rng: np.random.Generator, pixel_frame: F, bbox: Box) -> Projection[F]: 

26 """Create a test projection with random parameters. 

27 

28 Parameters 

29 ---------- 

30 rng 

31 Random number generator. 

32 pixel_frame 

33 Coordinate frame for the pixel grid. 

34 bbox 

35 Bounding box for the pixel grid. 

36 

37 Returns 

38 ------- 

39 `.Projection` 

40 A projection. Guaranteed to be FITS-representable and have no FITS 

41 approximation attached. 

42 """ 

43 header = { 

44 "CTYPE1": "RA---TAN", 

45 "CTYPE2": "DEC--TAN", 

46 "CRPIX1": rng.uniform(low=1, high=bbox.x.size), 

47 "CRPIX2": rng.uniform(low=1, high=bbox.y.size), 

48 "CRVAL1": rng.uniform(low=0.0, high=2 * np.pi), 

49 "CRVAL2": rng.uniform(low=-np.pi, high=np.pi), 

50 "CDELT1": (rng.uniform(low=0.18, high=0.22) * u.arcsec).to_value(u.deg), 

51 "CDELT2": (rng.uniform(low=0.18, high=0.22) * u.arcsec).to_value(u.deg), 

52 "CROTA1": rng.uniform(low=0.0, high=2 * np.pi), 

53 } 

54 fits_wcs = astropy.wcs.WCS(header) 

55 return Projection.from_fits_wcs( 

56 fits_wcs, pixel_frame, pixel_bounds=bbox, x0=bbox.x.start, y0=bbox.y.start 

57 )