Coverage for metadetect / lsst / util.py: 11%
309 statements
« prev ^ index » next coverage.py v7.13.1, created at 2026-01-24 01:37 -0800
1import logging
2from contextlib import contextmanager, ExitStack
3import ngmix
4import numpy as np
6logger = logging.getLogger(__name__)
9class ContextNoiseReplacer(object):
10 """
11 noise replacer that works as a context manager
13 Parameters
14 ----------
15 mbexp: lsst.afw.image.Exposure
16 The data
17 sources: lsst.afw.table.SourceCatalog
18 Catalog of sources
19 noise_image: array, optional
20 Optional noise image to use. If not sent one is generated.
22 Examples
23 --------
24 with ContextNoiseReplacer(exposure=exp, sources=sources) as replacer:
25 # do something
26 """
28 def __init__(self, exposure, sources, rng, config=None, noise_image=None):
29 from lsst.meas.base import NoiseReplacerConfig, NoiseReplacer
30 import lsst.afw.detection as afw_det
32 # Notes for metacal.
33 #
34 # For metacal we should generate a noise image so that the exact noise
35 # field is used for all versions of the metacal images. The assumption is
36 # that, because these noise data should contain no signal, metacal is not
37 # calibrating it. Thus it doesn't matter whether or not the noise field is
38 # representative of the full covariance of the true image noise. Rather by
39 # making the field the same for all metacal images we reduce variance in
40 # the calculation of the response
42 if config is None:
43 config = NoiseReplacerConfig()
45 # TODO DM needs to fix the crash
46 # config.noiseSource = 'variance'
47 config.noiseSeedMultiplier = rng.randint(0, 2**24)
49 if noise_image is None:
50 # TODO remove_poisson should be true for real data
51 noise_image = get_noise_image(exposure, rng=rng, remove_poisson=False)
53 footprints = {}
54 for source in sources:
55 parent_id = source.getParent()
56 fp = source.getFootprint()
57 heavy = afw_det.makeHeavyFootprint(fp, exposure.maskedImage)
58 footprints[source.getId()] = (parent_id, heavy)
59 # footprints = {
60 # source.getId(): (source.getParent(), source.getFootprint())
61 # for source in sources
62 # }
64 # This constructor will replace all detected pixels with noise in the
65 # image
66 self.replacer = NoiseReplacer(
67 config,
68 exposure=exposure,
69 footprints=footprints,
70 noiseImage=noise_image,
71 )
73 @contextmanager
74 def sourceInserted(self, source_id):
75 """
76 Context manager to insert a source
78 with replacer.sourceInserted(source_id):
79 # do something with exposure
80 """
81 self.insertSource(source_id)
83 try:
84 yield self
85 finally:
86 self.removeSource(source_id)
88 def insertSource(self, source_id):
89 """
90 Insert a source
91 """
92 self.replacer.insertSource(source_id)
94 def removeSource(self, source_id):
95 """
96 Remove a source
97 """
98 self.replacer.removeSource(source_id)
100 def end(self):
101 self.replacer.end()
103 def __enter__(self):
104 return self
106 def __exit__(self, exception_type, exception_value, traceback):
107 self.end()
110class MultibandNoiseReplacer(object):
111 """
112 noise replacer that works on multiple bands
114 Parameters
115 ----------
116 mbexp: lsst.afw.image.MultibandExposure
117 The data
118 sources: lsst.afw.table.SourceCatalog
119 Catalog of sources
121 Examples
122 --------
123 with MultibandNoiseReplacer(mbexp=mbexp, sources=sources) as replacer:
124 with replacer.insertSource(source_id):
125 # do something with exposures
126 """
127 def __init__(self, mbexp, sources, rng):
128 self.mbexp = mbexp
129 self.sources = sources
130 self.rng = rng
131 self._set_noise_replacers()
133 @contextmanager
134 def sourceInserted(self, source_id):
135 """
136 Context manager to insert a source
138 with replacer.sourceInserted(source_id):
139 # do something with exposures
140 """
141 self.insertSource(source_id)
143 try:
144 # usually won't use this yielded value
145 yield self.mbexp
146 finally:
147 self.removeSource(source_id)
149 def insertSource(self, source_id):
150 """
151 Insert a source
152 """
153 for replacer in self.noise_replacers:
154 replacer.insertSource(source_id)
156 def removeSource(self, source_id):
157 """
158 Remove a source
159 """
160 for replacer in self.noise_replacers:
161 replacer.removeSource(source_id)
163 def end(self):
164 """
165 end the noise replacment. Called automatically upon leaving the
166 context manager
167 """
168 self.exit_stack.close()
170 def _set_noise_replacers(self):
171 """
172 set a noise replacer for each exp and put it on the
173 context lib ExitStack for cleanup later
174 """
176 self.noise_replacers = []
177 self.exit_stack = ExitStack()
179 for exp in self.mbexp.singles:
180 replacer = ContextNoiseReplacer(
181 exposure=exp,
182 sources=self.sources,
183 rng=self.rng,
184 )
185 self.noise_replacers.append(replacer)
186 self.exit_stack.enter_context(replacer)
188 def __enter__(self):
189 return self
191 def __exit__(self, exception_type, exception_value, traceback):
192 self.end()
195def get_noise_replacer(exposure, sources, noise_image=None):
196 """
197 get a regular noise replacer for the input exposure and source list
199 Parameters
200 ----------
201 exposure: lsst.afw.image.ExposureF
202 The exposure data
203 sources: lsst.afw.table.SourceCatalog
204 The sources
205 noise_image: array, optional
206 Optional array of noise
208 Returns
209 -------
210 lsst.meas.base.NoiseReplacer
211 """
212 from lsst.meas.base import NoiseReplacerConfig, NoiseReplacer
214 # Notes for metacal.
215 #
216 # For metacal we should generate a noise image so that the exact noise
217 # field is used for all versions of the metacal images. The assumption is
218 # that, because these noise data should contain no signal, metacal is not
219 # calibrating it. Thus it doesn't matter whether or not the noise field is
220 # representative of the full covariance of the true image noise. Rather by
221 # making the field the same for all metacal images we reduce variance in
222 # the calculation of the response
224 noise_replacer_config = NoiseReplacerConfig()
225 footprints = {
226 source.getId(): (source.getParent(), source.getFootprint())
227 for source in sources
228 }
230 # This constructor will replace all detected pixels with noise in the
231 # image
232 return NoiseReplacer(
233 noise_replacer_config,
234 exposure=exposure,
235 footprints=footprints,
236 noiseImage=noise_image,
237 )
240def get_noise_image(exp, rng, remove_poisson):
241 """
242 get a noise image based on the input exposure
244 TODO gain correct separately in each amplifier, currently
245 averaged
247 Parameters
248 ----------
249 exp: afw.image.ExposureF
250 The exposure upon which to base the noise
251 rng: np.random.RandomState
252 The random number generator for making the noise image
253 remove_poisson: bool
254 If True, remove the poisson noise from the variance
255 estimate.
257 Returns
258 -------
259 MaskedImage
260 """
261 import lsst.afw.image as afw_image
263 noise_exp = afw_image.ExposureF(exp, deep=True)
265 signal = exp.image.array
266 variance = exp.variance.array
268 use = np.where(np.isfinite(variance) & np.isfinite(signal))
270 if remove_poisson:
271 gains = [
272 amp.getGain() for amp in exp.getDetector().getAmplifiers()
273 ]
274 mean_gain = np.mean(gains)
276 corrected_var = variance[use] - signal[use] / mean_gain
278 var = np.median(corrected_var)
279 else:
280 var = np.median(variance[use])
282 noise = rng.normal(scale=np.sqrt(var), size=signal.shape)
284 noise_exp.image.array[:, :] = noise
285 noise_exp.variance.array[:, :] = var
287 return noise_exp.getMaskedImage()
290def get_mbexp(exposures):
291 """
292 convert a list of exposures into an MultibandExposure
294 Parameters
295 ----------
296 exposures: [lsst.afw.image.ExposureF]
297 List of exposures of type F, D etc.
299 Returns
300 -------
301 lsst.afw.image.MultibandExposure
302 """
303 from lsst.afw.image import MultibandExposure
305 filters = [exp.getFilter().bandLabel for exp in exposures]
306 mbexp = MultibandExposure.fromExposures(filters, exposures)
308 for exp, sexp in zip(exposures, mbexp.singles):
309 sexp.setFilter(exp.getFilter())
310 sexp.setWcs(exp.getWcs())
312 return mbexp
315def copy_mbexp(mbexp, clear=False):
316 """
317 copy a MultibandExposure with psfs
319 clone() does not copy the psfs
321 Parameters
322 ----------
323 mbexp: lsst.afw.image.MultibandExposure
324 The exposures to copy
325 clear: bool, optional
326 If set to True, clear the data
328 Returns
329 -------
330 lsst.afw.image.MultibandExposure
331 """
333 new_mbexp = mbexp.clone()
335 # clone does not copy the psfs
336 for band in mbexp.bands:
337 psf = try_clone_psf(mbexp[band].getPsf())
338 new_mbexp[band].setPsf(psf)
340 for new_exp, exp in zip(new_mbexp.singles, mbexp.singles):
341 new_exp.setFilter(exp.getFilter())
342 new_exp.setWcs(exp.getWcs())
344 if clear:
345 new_mbexp.image.array[:, :, :] = 0
347 return new_mbexp
350def try_clone_psf(psf):
351 """
352 try to clone it, if not return a reference
353 """
354 try:
355 new_psf = psf.clone()
356 except RuntimeError:
357 # this happens on some psfs, not sure why
358 # proceed without a copy
359 new_psf = psf
361 return new_psf
364def coadd_exposures(exposures):
365 """
366 coadd a set of exposures, assuming they share the same wcs
368 Parameters
369 ----------
370 exposures: [lsst.afw.image.Exposure]
371 List of exposures to coadd
373 Returns
374 --------
375 lsst.afw.image.ExposureF
376 """
377 import lsst.geom as geom
378 import lsst.afw.image as afw_image
380 wsum = 0.0
382 for i, exp in enumerate(exposures):
384 shape = exp.image.array.shape
386 ycen, xcen = (np.array(shape) - 1)/2
387 cen = geom.Point2D(xcen, ycen)
389 psfobj = exp.getPsf()
390 this_psfim = psfobj.computeKernelImage(cen).array
392 if i == 0:
393 coadd_exp = afw_image.ExposureF(exp, deep=True)
394 coadd_exp.image.array[:, :] = 0.0
396 weight = np.zeros(shape, dtype='f4')
398 psf_im = this_psfim.copy()
399 psf_im[:, :] = 0
401 coadd_exp.mask.array |= exp.mask.array
403 w = np.where(exp.variance.array > 0)
404 medvar = np.median(exp.variance.array[w])
405 this_weight = 1.0/medvar
407 coadd_exp.image.array[w] += exp.image.array[w] * this_weight
408 psf_im += this_psfim * this_weight
410 weight[w] += 1.0/exp.variance.array[w]
412 wsum += this_weight
414 if wsum <= 0:
415 logger.info('found wsum <= 0')
416 return None
418 fac = 1.0/wsum
420 coadd_exp.image.array[:, :] *= fac
422 # the psf is always normalized
423 psf_im *= 1.0/psf_im.sum()
425 coadd_exp.variance.array[:, :] = np.inf
426 w = np.where(weight > 0)
427 coadd_exp.variance.array[w] = 1/weight[w]
429 coadd_psf = get_stack_kernel_psf(psf_im)
430 coadd_exp.setPsf(coadd_psf)
432 coadd_exp.setWcs(exposures[0].getWcs())
434 return coadd_exp
437def get_stack_kernel_psf(psf_image):
438 """
439 create a KernelPsf from the input image
441 Parameters
442 ----------
443 psf_image: array
444 The array data
446 Returns
447 -------
448 lsst.meas.algorithms.KernelPsf
449 """
450 import lsst.afw.image as afw_image
451 from lsst.meas.algorithms import KernelPsf
452 from lsst.afw.math import FixedKernel
454 return KernelPsf(
455 FixedKernel(
456 afw_image.ImageD(psf_image.astype(float))
457 )
458 )
461def coadd_mbobs(mbobs):
462 """
463 coadd a set of exposures, assuming they share the same wcs
465 Parameters
466 ----------
467 exposures: [lsst.afw.image.Exposure]
468 List of exposures to coadd
470 Returns
471 --------
472 lsst.afw.image.ExposureF
473 """
475 wsum = 0.0
477 meta = {}
478 for i, obslist in enumerate(mbobs):
479 obs = obslist[0]
480 meta.update(obs.meta)
482 shape = obs.image.shape
484 if i == 0:
485 coadd_image = np.zeros(shape, dtype='f4')
486 coadd_weight = np.zeros(shape, dtype='f4')
488 coadd_psf = np.zeros(obs.psf.image.shape)
490 w = np.where(obs.weight > 0)
491 this_weight = np.median(obs.weight[w])
493 coadd_image[:, :] += obs.image * this_weight
494 coadd_weight[:, :] += obs.weight
495 coadd_psf[:, :] += obs.psf.image * this_weight
497 wsum += this_weight
499 fac = 1.0/wsum
501 coadd_image[:, :] *= fac
503 # the psf is always normalized
504 coadd_psf *= 1.0/coadd_psf.sum()
506 # use the jacobians from the last obs
507 jac = obs.jacobian
508 psf_jac = obs.psf.jacobian
510 fake_noise = coadd_psf.max() / 1.e6
511 psf_weight = np.zeros(coadd_psf.shape)
512 psf_weight += (1.0/fake_noise**2)
514 psf_obs = ngmix.Observation(
515 image=coadd_psf,
516 weight=psf_weight,
517 jacobian=psf_jac,
518 )
519 output_obs = ngmix.Observation(
520 image=coadd_image,
521 weight=coadd_weight,
522 jacobian=jac,
523 psf=psf_obs,
524 meta=meta,
525 )
527 return output_obs
530def trim_odd_image(im):
531 """
532 trim an odd dimension image to by square and with equal distance from
533 canonical center to all edges
534 """
536 dims = im.shape
537 if dims[0] != dims[1]:
538 logger.debug('original dims: %s' % str(dims))
539 assert dims[0] % 2 != 0, 'image must have odd dims'
540 assert dims[1] % 2 != 0, 'image must have odd dims'
542 dims = np.array(dims)
543 cen = (dims-1)//2
544 cen = cen.astype('i4')
546 distances = (
547 cen[0]-0,
548 dims[0]-cen[0]-1,
549 cen[1]-0,
550 dims[1]-cen[1]-1,
551 )
552 logger.debug('distances: %s' % str(distances))
553 min_dist = min(distances)
555 start_row = cen[0] - min_dist
556 end_row = cen[0] + min_dist
557 start_col = cen[1] - min_dist
558 end_col = cen[1] + min_dist
560 # adding +1 for slices
561 new_im = im[
562 start_row:end_row+1,
563 start_col:end_col+1,
564 ].copy()
566 logger.debug('new dims: %s' % str(new_im.shape))
568 else:
569 new_im = im
571 return new_im
574def obs2exp(obs, exp=None, copy_mask_from='bmask', copy_psf=False):
575 """
576 copy ngmix.Observation data into an Exposure. The pixel data are copied,
577 and the weight is converted to variance.
579 If a complex WCS or PSF is needed, it is better to send an existing one.
580 The wcs will not be altered by this code.
582 The psf image can be optionally copied in as a KernelPsf
584 Parameters
585 ----------
586 obs: ngmix.Observation
587 The observation data
588 exp: lsst.afw.image.ExposureF, optional
589 Optional exposure into which the data are to copied. Note the psf is
590 not copied unless copy_psf is set to True. The wcs is not modified.
591 copy_mask_from: bool, optional
592 Copy from this mask into the exp mask.
593 copy_psf: bool, optional
594 If set to True, the psf is copied in as a KernelPsf(FixedKernel)
596 Returns
597 -------
598 exp: lsst.afw.image.ExposureF
599 Either a reference to the input exposure, or a new one if it was
600 created internally.
601 """
602 from lsst.meas.algorithms import KernelPsf
603 from lsst.afw.math import FixedKernel
604 import lsst.afw.image as afw_image
606 if exp is None:
607 ny, nx = obs.image.shape
608 exp = afw_image.ExposureF(nx, ny)
610 exp.image.array[:, :] = obs.image
612 exp.variance.array[:, :] = np.inf
614 if copy_mask_from == 'bmask':
615 mask = obs.bmask
616 elif copy_mask_from == 'ormask':
617 mask = obs.ormask
618 else:
619 raise RuntimeError(
620 f"copy_mask_from '{copy_mask_from}' should be 'bmask' or 'ormask'"
621 )
622 exp.mask.array[:, :] = mask
624 w = np.where(obs.weight > 0)
625 exp.variance.array[w] = 1.0/obs.weight[w]
627 if copy_psf:
628 psf_image = obs.psf.image
629 stack_psf = KernelPsf(
630 FixedKernel(
631 afw_image.ImageD(psf_image.astype(float))
632 )
633 )
634 exp.setPsf(stack_psf)
636 return exp
639def exp2obs(exp, copy_mask_to='ormask', store_exp=False):
640 """
641 convert an exposure to an observation. The wcs is linearized
642 and the psf is reconstructed as a kernel image.
644 The origin for the jacobian is set to the image center, relative to the
645 bounding box corner. The psf image is reconstructed at the center of the
646 image.
648 TODO do we ever need to do computeImage in this code?
650 Optionally, the original exposure can be stored in .meta so we can reverse
651 the process and go back to an exposure, copying in any changes to the image
652 data
654 Parameters
655 ----------
656 exp: lsst.afw.image.ExposureF
657 The exposure
658 copy_mask_to: str
659 Copy from the exp.mask into this attribute of the Observation. For
660 example, if set to 'ormask', the exposure mask is copied to the
661 obs.ormask and obs.bmask is set to zero.
662 store_exp: bool, optional
663 If set to True, store the original exposure in .meta['exposure']
665 Returns
666 -------
667 ngmix.Observation
668 """
670 wcs = exp.getWcs()
671 bbox = exp.getBBox()
673 # this is to be consistent with the coadd code
674 cen, _ = get_integer_center(
675 wcs=wcs,
676 bbox=bbox,
677 as_double=True,
678 )
680 jac = get_jacobian(exp=exp, cen=cen)
682 dims = exp.image.array.shape
683 weight = np.zeros(dims)
684 w = np.where(exp.variance.array > 0)
685 weight[w] = 1.0/exp.variance.array[w]
687 psf_obj = exp.getPsf()
688 psf_image = psf_obj.computeKernelImage(cen).array
690 assert psf_image.shape[0] == psf_image.shape[1], 'psf is not square'
691 assert psf_image.shape[0] % 2 != 0, 'psf dims are not odd'
692 psf_cen = (np.array(psf_image.shape)-1.0)/2.0
694 psf_jac = jac.copy()
695 psf_jac.set_cen(row=psf_cen[0], col=psf_cen[1])
697 psf_err = psf_image.max()*0.0001
698 psf_weight = psf_image*0 + 1.0/psf_err**2
700 psf_obs = ngmix.Observation(
701 image=psf_image,
702 weight=psf_weight,
703 jacobian=psf_jac,
704 )
706 if copy_mask_to == 'ormask':
707 ormask = exp.mask.array
708 bmask = ormask * 0
709 elif copy_mask_to == 'bmask':
710 bmask = exp.mask.array
711 ormask = bmask * 0
712 else:
713 raise RuntimeError(
714 f"copy_mask_to '{copy_mask_to}' should be 'bmask' or 'ormask'"
715 )
717 meta = {}
718 if store_exp:
719 meta['exposure'] = exp
721 return ngmix.Observation(
722 image=exp.image.array,
723 weight=weight,
724 bmask=bmask,
725 ormask=ormask,
726 jacobian=jac,
727 psf=psf_obs,
728 meta=meta,
729 )
732def get_jacobian(exp, cen):
733 """
734 get an ngmix jacobian at the specified location
736 Parameters
737 ----------
738 exp: lsst.afw.image.Exposure
739 The exposure data
740 cen: lsst.geom.Point2D
741 The position at which to get the jacobian. It is also used as the
742 center for the ngmix jacobian as relative to the corner of the bounding
743 box.
745 Returns
746 -------
747 ngmix.Jacobian
748 """
749 import lsst.geom as geom
751 wcs = exp.getWcs()
752 xy0 = exp.getXY0()
754 dm_jac = wcs.linearizePixelToSky(cen, geom.arcseconds)
755 matrix = dm_jac.getLinear().getMatrix()
757 relative_cen = cen - geom.Extent2D(xy0)
759 # ESS reverse engineered this convention mismatch. No documentation
760 # was found. Don't change this unless you know what you are doing.
762 return ngmix.Jacobian(
763 x=relative_cen.getX(),
764 y=relative_cen.getY(),
765 dudx=matrix[1, 1],
766 dudy=-matrix[1, 0],
767 dvdx=matrix[0, 1],
768 dvdy=-matrix[0, 0],
769 )
772def get_integer_center(wcs, bbox, as_double=False):
773 """
774 get the pixel and sky center of the coadd within the bbox
775 The pixel center is forced to be integer
777 Parameters
778 -----------
779 wcs: DM wcs
780 The wcs for the exposure
781 bbox: geom.Box2I
782 The bounding box for the exposure, possibly within a larger wcs system
784 Returns
785 -------
786 pixcen, skycen:
787 pixcen as Point2I, skycen as SpherePoint
788 """
789 from lsst.geom import Point2D, Point2I
791 # force integer location
792 pixcen = Point2I(bbox.getCenter())
793 skycen = wcs.pixelToSky(Point2D(pixcen))
795 if as_double:
796 pixcen = Point2D(pixcen)
798 return pixcen, skycen
801def get_stats_mask(*args, **kwargs):
802 """
803 Get a stats mask for use in getting image statistics.
805 ['BAD', 'EDGE', 'DETECTED', 'DETECTED_NEGATIVE', 'NO_DATA', 'BRIGHT']
807 Returns
808 -------
809 A list of mask planes
810 """
812 # these will be ignored when finding the image standard deviation
813 # stats_mask = ['BAD', 'SAT', 'EDGE', 'NO_DATA']
815 import lsst.afw.image as afw_image
816 afw_image.Mask.addMaskPlane('BRIGHT')
817 stats_mask = ['BAD', 'EDGE', 'DETECTED', 'DETECTED_NEGATIVE', 'NO_DATA', 'BRIGHT']
819 return stats_mask
822def get_detection_mask(*args, **kwargs):
823 """
824 Get a mask for detection. Regions with these flags set will not be searched
825 for objects.
827 Default is ['EDGE', 'NO_DATA', 'BRIGHT]
829 BRIGHT is defined in descwl_coadd, so it is not guaranteed to be present in
830 the global mask bit space. We add BRIGHT to detection mask. If it already
831 exists, it does not add a new plane and is harmless.
833 Returns
834 -------
835 A list of mask planes
836 """
838 import lsst.afw.image as afw_image
839 afw_image.Mask.addMaskPlane('BRIGHT')
840 mask = ['EDGE', 'NO_DATA', 'BRIGHT']
842 return mask
845def extract_multiband_coadd_data(coadd_data_list):
846 """
847 Convert a list of coadd data for a set of bands into MultibandExposure data
849 Side Effects
850 ------------
851 The masks are zerod, but the original ormasks are returned in the 'ormask'
852 item.
854 Parameters
855 ----------
856 coadd_data_list: list of dict
857 Each should be the output of descwl_coadd.make_coadd for a given band.
859 Returns
860 -------
861 data: dict
862 With items mbexp, noise_mbexp, mfrac_mbexp, ormasks
864 ormasks is a copy of .mask.array for each exp; the mask.array
865 are zerod for the exposures
866 """
868 exps = []
869 noise_exps = []
870 mfrac_exps = []
871 ormasks = []
872 for band, coadd_data in enumerate(coadd_data_list):
873 exp = coadd_data['coadd_exp']
874 noise_exp = coadd_data['coadd_noise_exp']
875 mfrac_exp = coadd_data['coadd_mfrac_exp']
877 ormasks.append(exp.mask.array.copy())
878 exp.mask.array[:, :] = 0
879 noise_exp.mask.array[:, :] = 0
880 mfrac_exp.mask.array[:, :] = 0
882 exps.append(exp)
883 noise_exps.append(noise_exp)
884 mfrac_exps.append(mfrac_exp)
886 mbexp = get_mbexp(exps)
887 noise_mbexp = get_mbexp(noise_exps)
888 mfrac_mbexp = get_mbexp(mfrac_exps)
890 return {
891 'mbexp': mbexp,
892 'noise_mbexp': noise_mbexp,
893 'mfrac_mbexp': mfrac_mbexp,
894 'ormasks': ormasks,
895 }
898def override_config(config, config_override: dict):
899 """Override the values in a Config instance with those in a dict.
901 The `config` object can have arbitrary level of nesting, and to override
902 the values, `config_override` should have the same nested structure.
903 To allow for arbitrary nesting, this function calls itself recursively.
905 Parameters
906 ----------
907 config : `lsst.pex.config.Config`
908 The configuration object to override.
909 config_override : `dict`
910 The dictionary of values to override the configuration with.
912 Raises
913 ------
914 AttributeError
915 Raised if a key in `config_override` is not an attribute of `config`.
916 """
917 for key, value in config_override.items():
918 if isinstance(value, dict):
919 subconfig = getattr(config, key)
920 # Use recursion to allow for arbitrarily nested config objects.
921 override_config(subconfig, value)
922 else:
923 if key == 'stamp_size':
924 config.toDict()[key] = value
925 else:
926 setattr(config, key, value)