spectral cube code example

Example: spectral cube

>>> import astropy.units as u
>>> from astropy.utils import data
>>> from spectral_cube import SpectralCube
>>> fn = data.get_pkg_data_filename('tests/data/example_cube.fits', 'spectral_cube')
>>> cube = SpectralCube.read(fn)
>>> print(cube)
SpectralCube with shape=(7, 4, 3) and unit=Jy / beam:
 n_x:      3  type_x: RA---ARC  unit_x: deg    range:    52.231466 deg:   52.231544 deg
 n_y:      4  type_y: DEC--ARC  unit_y: deg    range:    31.243639 deg:   31.243739 deg
 n_s:      7  type_s: VRAD      unit_s: m / s  range:    14322.821 m / s:   14944.909 m / s

# extract the subcube between 98 and 100 GHz
>>> slab = cube.spectral_slab(98 * u.GHz, 100 * u.GHz)  

# Ignore elements fainter than 1 Jy/beam
>>> masked_slab = slab.with_mask(slab > 1 Jy/beam)  

# Compute the first moment and write to file
>>> m1 = masked_slab.moment(order=1)  
>>> m1.write('moment_1.fits')