Source code for stsynphot.catalog

# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""This module handles :ref:`catalog spectra <stsynphot-spec-atlas>`."""

# STDLIB
import numbers

# THIRD-PARTY
import numpy as np

# ASTROPY
from astropy import units as u
from astropy.io import fits

# SYNPHOT
from synphot import exceptions as synexceptions
from synphot import units
from synphot.spectrum import SourceSpectrum
from synphot.utils import validate_totalflux

# LOCAL
from . import exceptions, stio

__all__ = ['reset_cache', 'get_catalog_index', 'grid_to_spec',
           'find_valid_g_phoenix', 'plot_phoenix']

_PARAM_NAMES = ['T_eff', 'metallicity', 'log_g']
_CACHE = {}  # Stores grid look-up parameters to reduce file I/O.


[docs]def reset_cache(): """Empty the catalog grid cache.""" global _CACHE _CACHE.clear()
def _par_from_parser(x): """Convert parser string to parameter value.""" if not isinstance(x, (numbers.Real, u.Quantity)): x = float(x) return x def _break_list(in_list, index, parameter): """Break input list into upper and lower lists.""" array = np.array([parameters[index] for parameters in in_list], dtype=np.float64) upper_array = array[array >= parameter] lower_array = array[array <= parameter] if upper_array.size == 0: raise exceptions.ParameterOutOfBounds( f"Parameter '{_PARAM_NAMES[index]}' exceeds data. " f"Max allowed={array.max()}, entered={parameter}.") if lower_array.size == 0: raise exceptions.ParameterOutOfBounds( f"Parameter '{_PARAM_NAMES[index]}' exceeds data. " f"Min allowed={array.min()}, entered={parameter}.") upper = upper_array.min() lower = lower_array.max() upper_list = [] lower_list = [] for i, parameters in enumerate(in_list): if array[i] >= parameter and array[i] <= upper: upper_list.append(parameters) if array[i] >= lower and array[i] <= parameter: lower_list.append(parameters) return upper_list, lower_list def _get_spectrum(parlist, catdir): """Get list of spectra for given parameter list and base name.""" name = parlist[3] filename = name.split('[')[0] column = name.split('[')[1][:-1] filename = stio.resolve_filename(catdir, *filename.split('/')) sp = SourceSpectrum.from_file(filename, flux_col=column) totflux = sp.integrate() try: validate_totalflux(totflux) except synexceptions.SynphotError: raise exceptions.ParameterOutOfBounds( f"Parameter '{parlist}' has no valid data.") result = [member for member in parlist] result.pop() result.append(sp) return result def _interpolate_spectrum(sp1, sp2, par): """Interpolate spectra to the given parameter value.""" spectrum1 = sp1.pop() spectrum2 = sp2.pop() par1 = sp1.pop() par2 = sp2.pop() if par1 == par2: sp = spectrum1 else: a = (par1 - par) / (par1 - par2) b = 1.0 - a sp = a * spectrum2 + b * spectrum1 result = [member for member in sp1] result.append(sp) return result
[docs]def get_catalog_index(gridname): """Extract catalog index (grid parameters). It is read once and then cached until the cache is cleared explicitly using :func:`reset_cache`. Parameters ---------- gridname : str See :func:`grid_to_spec`. Returns ------- cat_index : list List of ``[t_eff, metallicity, log_g, filename]``. catdir : str Directory containing the requested catalog. """ if gridname == 'ck04models': catdir = 'crgridck04$' elif gridname == 'k93models': catdir = 'crgridk93$' elif gridname == 'phoenix': catdir = 'crgridphoenix$' else: raise synexceptions.SynphotError( f'{gridname} is not a supported catalog grid.') catdir = stio.irafconvert(catdir) filename = stio.resolve_filename(catdir, 'catalog.fits') # If not cached, read from grid catalog and cache it if filename not in _CACHE: data = stio.read_catalog(filename) # EXT 1 _CACHE[filename] = [list(map(float, index.split(','))) + [data['FILENAME'][i]] for i, index in enumerate(data['INDEX'])] return _CACHE[filename], catdir
[docs]def grid_to_spec(gridname, t_eff, metallicity, log_g): """Extract spectrum from given catalog grid parameters. Interpolate if necessary. Grid parameters are read with :func:`get_catalog_index`. Parameters ---------- gridname : {'ck04models', 'k93models', 'phoenix'} Model to use: * ``ck04models`` - Castelli & Kurucz (2004) * ``k93models`` - Kurucz (1993) * ``phoenix`` - Allard et al. (2009) t_eff : str, float or `astropy.units.quantity.Quantity` Effective temperature of model. If not Quantity, assumed to be in Kelvin. If string (from parser), convert to Quantity. metallicity : str or float Metallicity of model. If string (from parser), convert to float. log_g : str or float Log surface gravity for model. If string (from parser), convert to float. Returns ------- sp : `synphot.spectrum.SourceSpectrum` Empirical source spectrum. Raises ------ stsynphot.exceptions.ParameterOutOfBounds Grid parameter out of bounds. synphot.exceptions.SynphotError Invalid inputs. """ indices, catdir = get_catalog_index(gridname) metallicity = _par_from_parser(metallicity) if isinstance(metallicity, u.Quantity): raise synexceptions.SynphotError( 'Quantity is not supported for metallicity.') log_g = _par_from_parser(log_g) if isinstance(log_g, u.Quantity): raise synexceptions.SynphotError( 'Quantity is not supported for log surface gravity.') t_eff = units.validate_quantity(_par_from_parser(t_eff), u.K).value list0, list1 = _break_list(indices, 0, t_eff) list2, list3 = _break_list(list0, 1, metallicity) list4, list5 = _break_list(list1, 1, metallicity) list6, list7 = _break_list(list2, 2, log_g) list8, list9 = _break_list(list3, 2, log_g) list10, list11 = _break_list(list4, 2, log_g) list12, list13 = _break_list(list5, 2, log_g) sp1 = _get_spectrum(list6[0], catdir) sp2 = _get_spectrum(list7[0], catdir) sp3 = _get_spectrum(list8[0], catdir) sp4 = _get_spectrum(list9[0], catdir) sp5 = _get_spectrum(list10[0], catdir) sp6 = _get_spectrum(list11[0], catdir) sp7 = _get_spectrum(list12[0], catdir) sp8 = _get_spectrum(list13[0], catdir) spa1 = _interpolate_spectrum(sp1, sp2, log_g) spa2 = _interpolate_spectrum(sp3, sp4, log_g) spa3 = _interpolate_spectrum(sp5, sp6, log_g) spa4 = _interpolate_spectrum(sp7, sp8, log_g) spa5 = _interpolate_spectrum(spa1, spa2, metallicity) spa6 = _interpolate_spectrum(spa3, spa4, metallicity) spa7 = _interpolate_spectrum(spa5, spa6, t_eff) sp = spa7[0] sp.meta['expr'] = (f'{gridname}(T_eff={t_eff:g},' f'metallicity={metallicity:g},log_g={log_g:g})') return sp
# NOTE: The following functions need refactoring if you want to generalize # them to work on all the supported catalogs. This is because the catalogs # do not share the same header structure. Generalization requires reading all # the spectra tables, not just header, which will have a significant # performance impact. # Also see https://github.com/spacetelescope/stsynphot_refactor/issues/45
[docs]def find_valid_g_phoenix(): # pragma: no cover """Find valid ``log_g`` values in the Phoenix catalog. .. note:: Takes time to run because it has to find the gaps by parsing the headers of individual data files in the catalog. Returns ------- valid_g : dict Dictionary mapping ``(t_eff, metallicity)`` to a list of valid ``log_g`` values. uniq_metallicity : list Unique metallicity values in the catalog. """ indices, catdir = get_catalog_index('phoenix') specfiles = {} valid_g = {} possible_g = set() uniq_metallicity = set() for a in indices: key = tuple(a[:2]) uniq_metallicity.add(a[1]) possible_g.add(a[2]) if key not in specfiles: specfiles[key] = a[3].split('[')[0] for key, spfile in specfiles.items(): hdr = fits.getheader(stio.resolve_filename( catdir, *spfile.split('/')))['LOGG*'] valid_g[key] = [] for val in hdr.values(): gval = float(val) if gval in possible_g: valid_g[key].append(gval) return valid_g, sorted(uniq_metallicity)
[docs]def plot_phoenix(filename=''): # pragma: no cover """Visualize the Phoenix catalog index (grid parameters). .. note:: Uses ``matplotlib``. .. note:: Takes time to run because it has to find the gaps by parsing the headers of individual data files in the catalog. Parameters ---------- filename : str If provided, plot is saved to given filename. """ import matplotlib.pyplot as plt valid_g, uniq_metallicity = find_valid_g_phoenix() n_plots = len(uniq_metallicity) ax_map = {} fig, axes = plt.subplots(nrows=3, ncols=4) axes = axes.flatten() n_axes = axes.size if n_plots > n_axes: raise ValueError(f'Need {n_plots} but only {n_axes} subplots created') for i, metallicity in enumerate(uniq_metallicity): ax_map[metallicity] = axes[i] for i in range(n_plots, n_axes): axes[i].remove() for key, log_g in valid_g.items(): metallicity = key[1] t_eff = [key[0]] * len(log_g) ax = ax_map[metallicity] ax.plot(t_eff, log_g, 'b,') ax.set_xlabel(r'$T_{\mathrm{eff}}$') ax.set_ylabel(r'$\log g$') ax.set_title(f'[M/H] = {metallicity:.2f}') ax.axvline(0, ls='--', lw=0.5, c='k') plt.tight_layout() plt.draw() if filename: fig.savefig(filename)