Coverage for python/lsst/faro/utils/phot_repeat.py: 16%

1# This file is part of faro. 

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# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <https://www.gnu.org/licenses/>. 

21 

22import numpy as np 

23import astropy.units as u 

24 

25from lsst.faro.utils.filtermatches import filterMatches 

26 

27__all__ = ("photRepeat", "calcPhotRepeat") 

28 

29 

30def photRepeat(matchedCatalog, magName=None, nMinPhotRepeat=50, **filterargs): 

31 """Measure the photometric repeatability of a set of observations. 

32 

33 Parameters 

34 ---------- 

35 matchedCatalog : `lsst.afw.table.base.Catalog` 

36 `~lsst.afw.table.base.Catalog` object as created by 

37 `~lsst.afw.table.multiMatch` matching of sources from multiple visits. 

38 magName : `str` 

39 Name of the magnitude field. Default "slot_PsfFlux_mag". 

40 nMinPhotRepeat : `int` 

41 Minimum number of sources required to return a measurement. 

42 **filterargs 

43 Additional arguments to pass to `filterMatches` for catalog filtering. 

44 

45 Returns 

46 ------- 

47 photo_resid_meas : `dict` 

48 Photometric repeatability statistics and related quantities as measured 

49 by `calcPhotRepeat`. Returns NaN values if there are fewer than 

50 nMinPhotRepeat sources in the matched catalog. 

51 """ 

52 if magName is None: 

53 magName = "slot_PsfFlux_mag" 

54 filteredCat = filterMatches(matchedCatalog, **filterargs) 

55 magKey = filteredCat.schema.find(magName).key 

56 

57 # Require at least nMinPhotRepeat objects to calculate the repeatability: 

58 if filteredCat.count > nMinPhotRepeat: 

59 phot_resid_meas = calcPhotRepeat(filteredCat, magKey) 

60 # Check that the number of stars with >2 visits is >nMinPhotRepeat: 

61 okcount = phot_resid_meas["count"] > 2 

62 if np.sum(okcount) > nMinPhotRepeat: 

63 return phot_resid_meas 

64 else: 

65 return {"nomeas": np.nan * u.mmag} 

66 else: 

67 return {"nomeas": np.nan * u.mmag} 

68 

69 

70def calcPhotRepeat(matches, magKey): 

71 """Calculate the photometric repeatability of a set of measurements. 

72 

73 Parameters 

74 ---------- 

75 matches : `lsst.afw.table.GroupView` 

76 `~lsst.afw.table.GroupView` of sources matched between visits using 

77 MultiMatch, as provided by `lsst.faro.utils.matcher.matchCatalogs`. 

78 magKey : `lsst.afw.table` schema key 

79 Magnitude column key in the ``GroupView``. 

80 E.g., ``magKey = allMatches.schema.find("slot_ModelFlux_mag").key`` 

81 where ``allMatches`` is the result of `lsst.afw.table.MultiMatch.finish()`. 

82 

83 Returns 

84 ------- 

85 statistics : `dict` 

86 Repeatability statistics and ancillary quantities calculated from the 

87 input ``GroupView`` matched catalog. Fields are: 

88 - ``count``: array of number of nonzero magnitude measurements for each 

89 input source. 

90 - ``magMean``: `~astropy.unit.Quantity` array of mean magnitudes, in mag, 

91 for each input source. 

92 - ``rms``: `~astropy.unit.Quantity` array of RMS photometric repeatability 

93 about the mean, in mmag, for each input source. 

94 - ``repeatability``: scalar `~astropy.unit.Quantity` of the median ``rms``. 

95 This is calculated using all sources with more than 2 magnitude 

96 measurements, and reported in mmag. 

97 - ``magResid``: `~astropy.unit.Quantity` array for each input source, 

98 containing the magnitude residuals, in mmag, with respect to ``magMean``. 

99 """ 

100 matches_rms = (matches.aggregate(np.nanstd, field=magKey) * u.mag).to(u.mmag) 

101 matches_count = matches.aggregate(np.count_nonzero, field=magKey) 

102 matches_mean = matches.aggregate(np.mean, field=magKey) * u.mag 

103 magResid = [] 

104 for gp in matches.groups: 

105 magResid.append(((gp[magKey] - np.mean(gp[magKey])) * (u.mag)).to(u.mmag)) 

106 magResid = np.array(magResid, dtype="object") 

107 okrms = matches_count > 2 

108 if np.sum(okrms) > 0: 

109 return { 

110 "count": matches_count, 

111 "magMean": matches_mean, 

112 "rms": matches_rms, 

113 "repeatability": np.median(matches_rms[okrms]), 

114 "magResid": magResid, 

115 } 

116 else: 

117 return { 

118 "count": 0, 

119 "magMean": np.nan * u.mag, 

120 "rms": np.nan * u.mmag, 

121 "repeatability": np.nan * u.mmag, 

122 "magDiffs": 0 * u.mmag, 

123 }