Spectrum Arithmetic

Specutils sports the ability to perform arithmetic operations over spectrum data objects. There is full support for propagating unit information.

Note

Spectrum arithmetic requires that the two spectrum objects have compatible WCS information.

Warning

Specutils does not currently implement interpolation techniques for converting spectral axes information from one WCS source to another.

Basic Arithmetic

Arithmetic support includes addition, subtract, multiplication, and division.

>>> from specutils import Spectrum1D
>>> import astropy.units as u
>>> import numpy as np

>>> rng = np.random.default_rng(12345)
>>> spec1 = Spectrum1D(spectral_axis=np.arange(1, 50) * u.nm, flux=rng.random(49)*u.Jy)
>>> spec2 = Spectrum1D(spectral_axis=np.arange(1, 50) * u.nm, flux=rng.random(49)*u.Jy)
>>> spec3 = spec1 + spec2
>>> spec3  
<Spectrum1D(flux=[0.8559405665668484 ... 0.9711264429515736] Jy (shape=(49,), mean=0.91592 Jy); spectral_axis=<SpectralAxis
   (observer to target:
      radial_velocity=0.0 km / s
      redshift=0.0)
  [ 1.  2.  3. ... 47. 48. 49.] nm> (length=49))>

Propagation of Uncertainties

Arithmetic operations also support the propagation of unceratinty information.

>>> from astropy.nddata import StdDevUncertainty

>>> rng = np.random.default_rng(12345)
>>> wave = np.arange(10) * u.nm
>>> spec1 = Spectrum1D(spectral_axis=wave,
...                    flux=rng.random(10)*u.Jy,
...                    uncertainty=StdDevUncertainty(rng.random(10) * 0.1))
>>> spec2 = Spectrum1D(spectral_axis=wave,
...                    flux=rng.random(10)*u.Jy,
...                    uncertainty=StdDevUncertainty(rng.random(10) * 0.1))
>>> spec1.uncertainty
StdDevUncertainty([0.02482457, 0.09488812, 0.06672375, 0.00958979,
                   0.04418397, 0.08864799, 0.06974535, 0.03264729,
                   0.07339282, 0.0220135 ])
>>> spec2.uncertainty
StdDevUncertainty([0.08547419, 0.06016212, 0.09319884, 0.07247814,
                   0.08605513, 0.09293378, 0.0546186 , 0.0937673 ,
                   0.04949879, 0.02737732])
>>> spec3 = spec1 + spec2
>>> spec3.uncertainty
StdDevUncertainty([0.08900616, 0.11235317, 0.11462147, 0.07310981,
                   0.09673525, 0.12843346, 0.08858671, 0.09928822,
                   0.08852478, 0.03512992])

Reference/API

Classes

OneDSpectrumMixin()

Class Inheritance Diagram