Coverage for python/lsst/atmospec/dispersion.py: 34%
25 statements
« prev ^ index » next coverage.py v6.4.1, created at 2022-06-26 02:00 -0700
« prev ^ index » next coverage.py v6.4.1, created at 2022-06-26 02:00 -0700
1# This file is part of atmospec.
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/>.
22import numpy as np
24import lsst.log as lsstLog
27__all__ = ['DispersionRelation']
30class DispersionRelation(object):
31 def __init__(self, observedLines, spectralLines):
32 """The dispersion relation, relating pixel to wavelength and vice versa
34 Parameters:
35 -----------
36 observedLines : `list` of `float`
37 The central wavelength of the observed lines in the spectrum in pix
39 spectralLines : `list` of `float`
40 The central wavelength of the spectral lines present in the source
41 in nm.
43 Notes:
44 ------
45 The current implementation just supplies linear transformations
46 but future extensions can support higher order polynomials,
47 spline-fits, distortions etc
48 """
49 self.observedLines = observedLines
50 self.spectralLines = spectralLines
52 self.log = lsstLog.Log.getLogger('atmospec.dispersionRelation')
53 self.pix2wlCoeffs = self._calcCoefficients()
55 def _calcCoefficients(self):
56 if((self.observedLines is None) or (self.spectralLines is None)):
57 self.log.warn('Missing input for _calcCoefficients, default transformation: 1 to 1 ')
58 self.observedLines = [1, 2]
59 self.spectralLines = [1, 2]
60 pix2wlCoeffs = np.polyfit(self.observedLines, self.spectralLines, deg=1)
62 # xxx change to debug
63 self.log.info('Pixel -> Wavelength linear transformation coefficients : ' + str(pix2wlCoeffs))
64 return pix2wlCoeffs
66 def Wavelength2Pixel(self, wavelength):
67 """Currently just a linear transform"""
68 wavelength = np.asarray(wavelength, dtype=np.float64)
69 coef = self.pix2wlCoeffs
70 return (wavelength-coef[1]) / coef[0]
72 def Pixel2Wavelength(self, pixel):
73 """Currently just a linear transform"""
74 pixel = np.asarray(pixel, dtype=np.float64)
75 coef = self.pix2wlCoeffs
76 return np.array(coef[1] + coef[0] * pixel)