Source code for pyspeckit.spectrum.models.template

Spectral Template Fitter

A tool to find the optimal shift and scaling for a given template model.

Module API
from ..interpolation import interp,_interp
import numpy as np
from . import model

[docs]def spectral_template_generator(template_spectrum, xshift_units='km/s', left=0, right=0): """ Given a spectral_template, return a model function with scale and shift as free parameters. Parameters ---------- template_spectrum: `pyspeckit.spectrum.classes.Spectrum` The template spectrum to fit xshift_units: str The units of the shift parameter left/right: float The left and right edge parameters used for extrapolating outside the template if the template is smaller than the input spectrum. These cannot be NaN. Returns ------- spectral_template: function The model function that interpolates the template onto the given X-axis """ def spectral_template(xarr, scale, xshift, xshift_units=xshift_units): """ Given a template Spectrum (which should be a Spectrum instance), scale & shift it """ shift = xarr.x_to_coord(xshift, xshift_units) model = scale * _interp(xarr, template_spectrum.xarr.as_unit(xarr.unit)+shift,, left=left, right=right, ) return model return spectral_template
[docs]def template_fitter(template_spectrum, xshift_units='km/s'): """ Generator for Spectral Template fitter class Parameters ---------- template_spectrum : pyspeckit.Spectrum A valid spectrum to be scaled and shifted to match the input xshift_units : str in pyspeckit.units.unit_type_dict The units of the shift to fit. If you're using a velocity unit, make sure there's a reference X-unit for both the template spectrum and the input spectrum. Examples -------- >>> template = pyspeckit.Spectrum("template_spectrum.fits") >>> dataspec = pyspeckit.Spectrum("DataSpectrum.fits") >>> template_fitter = pyspeckit.models.template_fitter(template, ... xshift_units='angstroms') >>> dataspec.Registry.add_fitter('template',template_fitter, 2) >>> dataspec.specfit(fittype='template',guesses=[1,0]) >>> print dataspec.specfit.parinfo """ modelfunc = spectral_template_generator(template_spectrum, xshift_units=xshift_units) myclass = model.SpectralModel(modelfunc, 2, parnames=['scale','shift'], parlimited=[(True,False),(False,False)], parlimits=[(0,0), (0,0)], shortvarnames=('A',r'\Delta x'), centroid_par='shift',) myclass.__name__ = "spectral_template" return myclass