Commit c748921e authored by Yannick Roehlly's avatar Yannick Roehlly Committed by Simon Conseil

Add a medium parameter to WaveCoord.coord

parent df4f7ede
......@@ -3,6 +3,9 @@
Development version, not released yet.
- The `WaveCoord.coord` now accepts a medium to force getting the air or vacuum
wavelength coordinates.
3.1 (03/04/2019)
......@@ -1640,7 +1640,7 @@ class WaveCoord:
atol=1E-2, rtol=0) and
self.wcs.wcs.ctype[0] == other.wcs.wcs.ctype[0])
def coord(self, pixel=None, unit=None):
def coord(self, pixel=None, unit=None, medium=None):
"""Return the coordinate corresponding to pixel.
If pixel is None (default value), the full coordinate array is
......@@ -1649,9 +1649,13 @@ class WaveCoord:
pixel : int, array or None.
pixel value.
Pixel value.
unit : `astropy.units.Unit`
type of the wavelength coordinates
Unit of the wavelength coordinates
medium : str or None
Medium in which the wavelengths are returned: 'air' or 'vacuum'.
If None (default), the wavelength corresponding to the spectrum
CTYPE are returned.
......@@ -1669,7 +1673,25 @@ class WaveCoord:
res = self.wcs.wcs_pix2world(pixelarr, 0)[0]
if unit is not None:
res = (res * self.unit).to(unit).value
return res[0] if np.isscalar(pixel) else res
result = res[0] if np.isscalar(pixel) else res
if medium is not None:
if medium not in ['air', 'vacuum']:
raise ValueError("Unknown 'medium' parameter value.")
ctype = self.wcs.wcs.ctype[0] # Wave type
if ctype[:4] not in ['WAVE', 'AWAV']:
raise ValueError("No method to convert from %s to %s." %
(ctype, medium))
from .spectrum import airtovac, vactoair # To avoid circ. import
if medium == "air" and ctype.startswith("WAVE"):
result = vactoair(result)
elif medium == "vacuum" and ctype.startswith("AWAV"):
result = airtovac(result)
return result
def pixel(self, lbda, nearest=False, unit=None):
"""Return the decimal pixel corresponding to the wavelength lbda.
......@@ -36,7 +36,9 @@ import numpy as np
from astropy import wcs as pywcs
from import fits
from mpdaf.obj import WCS, WaveCoord, deg2sexa, sexa2deg, determine_refframe
from mpdaf.obj.spectrum import airtovac, vactoair
from numpy.testing import assert_allclose, assert_array_equal
import pytest
from mpdaf.tests.utils import get_data_file
......@@ -160,6 +162,29 @@ class TestWaveCoord:
wave2 = wave.copy()
assert wave.isEqual(wave2)
def test_coord(self):
"""WaveCoord class: testing getting the coordinates"""
wave = WaveCoord(crval=0, cunit=u.nm, shape=10)
# By default the CTYPE is LINEAR and can't be converted to air or
# vacuum.
with pytest.raises(ValueError):
with pytest.raises(ValueError):
wave.wcs.wcs.ctype = ['WAVE']
with pytest.raises(ValueError):
# Unknown parameter value
wave.coord(medium='vacuum'), np.arange(10))
wave.coord(medium='air'), vactoair(np.arange(10)))
wave.wcs.wcs.ctype = ['AWAV']
wave.coord(medium='air'), np.arange(10))
wave.coord(medium='vacuum'), airtovac(np.arange(10)))
def test_coord_transform(self):
"""WaveCoord class: testing coordinates transformations"""
wave = WaveCoord(crval=0, cunit=u.nm, shape=10)
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