The computation of all the cosmology-dependent quantities has been...

The computation of all the cosmology-dependent quantities has been consolidated in pcigale/utils/cosmology.py and optimised. This leads to a slightly faster startup, in particular when there are many objects to fit, and it makes it easier to change the cosmology.

CHANGELOG.md

@@ -13,6 +13,7 @@
 - Some lines have been made slightly thicker in SED plots so the different components are more visible. (Médéric Boquien)
 - The colours in the SED plots have been tweaked for aesthetic reasons. (Médéric Boquien)
 - The markers for the observed fluxes in the SED plots have been tweaked to improve readability. (Médéric Boquien)
+- The computation of all the cosmology-dependent quantities has been consolidated in pcigale/utils/cosmology.py and optimised. This leads to a slightly faster startup, in particular when there are many objects to fit, and it makes it easier to change the cosmology. (Médéric Boquien)
 ### Fixed
 - Make sure we can plot the PDF of equivalent widths. (Médéric Boquien)
 - Fix a crash when generating a mock catalogue containing intensive properties. (Médéric Boquien)

pcigale/analysis_modules/pdf_analysis/utils.py

@@ -8,7 +8,7 @@
 from functools import lru_cache
 
 from astropy import log
-from astropy.cosmology import WMAP7 as cosmo
+from ...utils.cosmology import luminosity_distance
 import numpy as np
 from scipy import optimize
 from scipy.constants import parsec
@@ -48,11 +48,7 @@ def compute_corr_dz(model_z, obs):
         Object containing the distance and redshift of an object
 
     """
-    if model_z == 0.:
-        mod_distance = 10. * parsec
-    else:
-        mod_distance = cosmo.luminosity_distance(model_z).value * 1e6 * parsec
-    return (obs.distance / mod_distance) ** 2. * \
+    return (obs.distance / luminosity_distance(model_z)) ** 2. * \
            (1. + model_z) / (1. + obs.redshift)
 
 

pcigale/managers/observations.py

@@ -3,11 +3,11 @@
 # Licensed under the CeCILL-v2 licence - see Licence_CeCILL_V2-en.txt
 # Author: Médéric Boquien
 
-from astropy.cosmology import WMAP7 as cosmo
 from astropy.table import Column
 import numpy as np
 from scipy.constants import parsec
 
+from ..utils.cosmology import luminosity_distance
 from ..utils.io import read_table
 from .utils import get_info
 
@@ -299,11 +299,8 @@ class Observation(object):
         if 'distance' in row.colnames and np.isfinite(row['distance']):
             self.distance = row['distance'] * parsec * 1e6
         else:
-            if self.redshift == 0.:
-                self.distance = 10. * parsec
-            elif self.redshift > 0.:
-                self.distance = cosmo.luminosity_distance(self.redshift).value \
-                                * 1e6 * parsec
+            if self.redshift >= 0.:
+                self.distance = luminosity_distance(self.redshift)
             else:
                 self.distance = np.nan
         self.flux = {k: row[k] for k in cls.bands

pcigale/sed_modules/redshifting.py

@@ -23,7 +23,7 @@ from collections import OrderedDict
 import numpy as np
 from scipy.constants import parsec
 from scipy.special import factorial
-from astropy.cosmology import WMAP7 as cosmology
+from ..utils.cosmology import age, luminosity_distance
 
 from . import SedModule
 
@@ -163,13 +163,8 @@ class Redshifting(SedModule):
             raise Exception(f"The redshift provided is negative "
                             f"({self.redshift}).")
 
-        self.universe_age = cosmology.age(self.redshift).value * 1000.
-        if self.redshift == 0.:
-            self.luminosity_distance = 10. * parsec
-        else:
-            self.luminosity_distance = (
-                cosmology.luminosity_distance(self.redshift).value * 1e6 *
-                parsec)
+        self.universe_age = age(self.redshift)
+        self.luminosity_distance = luminosity_distance(self.redshift)
         # We do not define the values of the IGM attenuation component yet.
         # This is because we need the wavelength grid for that first. This
         # will be assigned on the first call.

pcigale/utils/cosmology.py

+# -*- coding: utf-8 -*-
+# Licensed under the CeCILL-v2 licence - see Licence_CeCILL_V2-en.txt
+
+from functools import lru_cache
+
+from astropy.cosmology import WMAP7 as _cosmo
+from scipy.constants import parsec
+
+
+@lru_cache(maxsize=None)
+def luminosity_distance(redshift):
+    """Computes the luminosity distance in m for a given redshift. If the
+    redshift is 0, then we assume a distance of 10 pc.
+
+    Parameter
+    ---------
+    redshift: scalar
+        Redshift of the object
+
+    Returns
+    -------
+    luminosity_distance: scalar
+        Luminosity distance to the object in m
+    """
+    if redshift > 0:
+        return _cosmo.luminosity_distance(redshift).value * 1e6 * parsec
+    return 10. * parsec
+
+
+@lru_cache(maxsize=None)
+def age(redshift):
+    """Computes the age of the universe in Myr at a given redshift.
+
+    Parameter
+    ---------
+    redshift: scalar
+        Redshift of the object
+
+    Returns
+    -------
+    age: float
+        Age of the universe in Myr at the corresponding redshift
+    """
+    return _cosmo.age(redshift).value * 1000.