Add a medium parameter to WaveCoord.coord (c748921e) · Commits · MUSE / mpdaf

CHANGELOG

+3 −0

Original line number	Diff line number	Diff line
		@@ -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)
		----------------

lib/mpdaf/obj/coords.py

+26 −4

Original line number	Diff line number	Diff line
		@@ -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:
		Parameters
		----------
		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.

		Returns
		-------
		@@ -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.

lib/mpdaf/obj/tests/test_coords.py

+25 −0

Original line number	Diff line number	Diff line
		@@ -36,7 +36,9 @@ import numpy as np
		from astropy import wcs as pywcs
		from astropy.io 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):
		wave.coord(medium='air')
		with pytest.raises(ValueError):
		wave.coord(medium='vacuum')
		wave.wcs.wcs.ctype = ['WAVE']
		with pytest.raises(ValueError):
		# Unknown parameter value
		wave.coord(medium='vacuu')
		np.testing.assert_array_equal(
		wave.coord(medium='vacuum'), np.arange(10))
		np.testing.assert_array_equal(
		wave.coord(medium='air'), vactoair(np.arange(10)))
		wave.wcs.wcs.ctype = ['AWAV']
		np.testing.assert_array_equal(
		wave.coord(medium='air'), np.arange(10))
		np.testing.assert_array_equal(
		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)