def redshift_distance(cosmology=None, kind="comoving", **atzkw):
"""Convert quantities between redshift and distance.
Care should be taken to not misinterpret a relativistic, gravitational, etc
redshift as a cosmological one.
Parameters
----------
cosmology : `~astropy.cosmology.Cosmology`, str, or None, optional
A cosmology realization or built-in cosmology's name (e.g. 'Planck18').
If None, will use the default cosmology
(controlled by :class:`~astropy.cosmology.default_cosmology`).
kind : {'comoving', 'lookback', 'luminosity'} or None, optional
The distance type for the Equivalency.
Note this does NOT include the angular diameter distance as this
distance measure is not monotonic.
**atzkw
keyword arguments for :func:`~astropy.cosmology.z_at_value`
Returns
-------
`~astropy.units.equivalencies.Equivalency`
Equivalency between redshift and temperature.
Examples
--------
>>> import astropy.units as u
>>> import astropy.cosmology.units as cu
>>> from astropy.cosmology import WMAP9
>>> z = 1100 * cu.redshift
>>> z.to(u.Mpc, cu.redshift_distance(WMAP9, kind="comoving")) # doctest: +FLOAT_CMP
<Quantity 14004.03157418 Mpc>
"""
from astropy.cosmology import default_cosmology, z_at_value
# get cosmology: None -> default and process str / class
cosmology = cosmology if cosmology is not None else default_cosmology.get()
with default_cosmology.set(cosmology): # if already cosmo, passes through
cosmology = default_cosmology.get()
allowed_kinds = ('comoving', 'lookback', 'luminosity')
if kind not in allowed_kinds:
raise ValueError(f"`kind` is not one of {allowed_kinds}")
method = getattr(cosmology, kind + "_distance")
def z_to_distance(z):
"""Redshift to distance."""
return method(z)
def distance_to_z(d):
"""Distance to redshift."""
return z_at_value(method, d << u.Mpc, **atzkw)
return u.Equivalency([(redshift, u.Mpc, z_to_distance, distance_to_z)],
"redshift_distance", {
'cosmology': cosmology,
"distance": kind
})
def test_distance(self, kind):
"""Test distance equivalency."""
cosmo = Planck13
z = 15 * cu.redshift
dist = getattr(cosmo, kind + "_distance")(z)
default_cosmo = default_cosmology.get()
assert default_cosmo != cosmo # shows changing default
# 1) without specifying the cosmology
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(distance=kind)
assert_quantity_allclose(z.to(u.Mpc, equivalency), dist)
# showing the answer changes if the cosmology changes
# this test uses the default cosmology
equivalency = cu.with_redshift(distance=kind)
assert_quantity_allclose(z.to(u.Mpc, equivalency),
getattr(default_cosmo, kind + "_distance")(z))
assert not u.allclose(getattr(default_cosmo, kind + "_distance")(z), dist)
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, distance=kind)
assert_quantity_allclose(z.to(u.Mpc, equivalency), dist)
assert_quantity_allclose(dist.to(cu.redshift, equivalency), z)
# Test atzkw
# this is really just a test that 'atzkw' doesn't fail
equivalency = cu.with_redshift(cosmo, distance=kind, atzkw={"ztol": 1e-10})
assert_quantity_allclose(dist.to(cu.redshift, equivalency), z)
def redshift_temperature(cosmology=None, **atzkw):
"""Convert quantities between redshift and CMB temperature.
Care should be taken to not misinterpret a relativistic, gravitational, etc
redshift as a cosmological one.
Parameters
----------
cosmology : `~astropy.cosmology.Cosmology`, str, or None, optional
A cosmology realization or built-in cosmology's name (e.g. 'Planck18').
If None, will use the default cosmology
(controlled by :class:`~astropy.cosmology.default_cosmology`).
**atzkw
keyword arguments for :func:`~astropy.cosmology.z_at_value`
Returns
-------
`~astropy.units.equivalencies.Equivalency`
Equivalency between redshift and temperature.
"""
from astropy.cosmology import default_cosmology, z_at_value
# get cosmology: None -> default and process str / class
cosmology = cosmology if cosmology is not None else default_cosmology.get()
with default_cosmology.set(cosmology): # if already cosmo, passes through
cosmology = default_cosmology.get()
def z_to_Tcmb(z):
return cosmology.Tcmb(z)
def Tcmb_to_z(T):
return z_at_value(cosmology.Tcmb, T << u.K, **atzkw)
return u.Equivalency([(redshift, u.K, z_to_Tcmb, Tcmb_to_z)],
"redshift_temperature", {'cosmology': cosmology})
def test_temperature(self, cosmo):
"""Test temperature equivalency component."""
default_cosmo = default_cosmology.get()
z = 15 * cu.redshift
Tcmb = cosmo.Tcmb(z)
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(Tcmb=True)
assert_quantity_allclose(z.to(u.K, equivalency), Tcmb)
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
# showing the answer changes if the cosmology changes
# this test uses the default cosmology
equivalency = cu.with_redshift(Tcmb=True)
assert_quantity_allclose(z.to(u.K, equivalency), default_cosmo.Tcmb(z))
assert default_cosmo.Tcmb(z) != Tcmb
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, Tcmb=True)
assert_quantity_allclose(z.to(u.K, equivalency), Tcmb)
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
# Test `atzkw`
# this is really just a test that 'atzkw' doesn't fail
equivalency = cu.with_redshift(cosmo, Tcmb=True, atzkw={"ztol": 1e-10})
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
def test_redshift_temperature():
"""Test :func:`astropy.cosmology.units.redshift_temperature`."""
cosmo = Planck13.clone(Tcmb0=3 * u.K)
default_cosmo = default_cosmology.get()
z = 15 * cu.redshift
Tcmb = cosmo.Tcmb(z)
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.redshift_temperature()
assert_quantity_allclose(z.to(u.K, equivalency), Tcmb)
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
# showing the answer changes if the cosmology changes
# this test uses the default cosmology
equivalency = cu.redshift_temperature()
assert_quantity_allclose(z.to(u.K, equivalency), default_cosmo.Tcmb(z))
assert default_cosmo.Tcmb(z) != Tcmb
# 2) Specifying the cosmology
equivalency = cu.redshift_temperature(cosmo)
assert_quantity_allclose(z.to(u.K, equivalency), Tcmb)
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
# Test `atzkw`
equivalency = cu.redshift_temperature(cosmo, ztol=1e-10)
assert_quantity_allclose(Tcmb.to(cu.redshift, equivalency), z)
def execute(self, parameters={}):
r'''Run a pipeline.
This function runs a pipeline of functions to generate variables and
the columns of a set of tables. It uses a Directed Acyclic Graph to
determine a non-blocking order of execution that resolves any
dependencies, see [1]_.
Parameters
----------
parameters : dict
Updated parameter values for this execution.
References
----------
.. [1] https://networkx.github.io/documentation/stable/
'''
# update parameter state
self.parameters.update(parameters)
# initialise state object
self.state = copy(self.parameters)
# Initialise cosmology from config parameters or use astropy default
if self.cosmology:
self.state['cosmology'] = self.get_value(self.cosmology)
else:
self.state['cosmology'] = default_cosmology.get()
# Execute pipeline setting state cosmology as the default
with default_cosmology.set(self.state['cosmology']):
# go through the jobs in dependency order
for job in networkx.topological_sort(self.dag):
if job in self.skip_jobs:
continue
elif job in self.config:
settings = self.config.get(job)
self.state[job] = self.get_value(settings)
else:
table, column = job.split('.')
settings = self.table_config[table][column]
names = [n.strip() for n in column.split(',')]
if len(names) > 1:
# Multi-column assignment
t = Table(self.get_value(settings), names=names)
self.state[table].add_columns(t.columns.values())
else:
# Single column assignment
self.state[table][column] = self.get_value(settings)
def test_distance_off(self, cosmo):
"""Test ``with_redshift`` with the distance off."""
z = 15 * cu.redshift
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(distance=None)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'Mpc'"):
z.to(u.Mpc, equivalency)
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, distance=None)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'Mpc'"):
z.to(u.Mpc, equivalency)
def test_temperature_off(self, cosmo):
"""Test ``with_redshift`` with the temperature off."""
z = 15 * cu.redshift
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(Tcmb=False)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'K'"):
z.to(u.K, equivalency)
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, Tcmb=False)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'K'"):
z.to(u.K, equivalency)
def test_hubble_off(self, cosmo):
"""Test ``with_redshift`` with Hubble off."""
unit = u.km / u.s / u.Mpc
z = 15 * cu.redshift
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(hubble=False)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'km / "):
z.to(unit, equivalency)
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, hubble=False)
with pytest.raises(u.UnitConversionError, match="'redshift' and 'km / "):
z.to(unit, equivalency)
def with_redshift(cosmology=None, *, Tcmb=True, atzkw=None):
"""Convert quantities between measures of cosmological distance.
Note: by default all equivalencies are on and must be explicitly turned off.
Care should be taken to not misinterpret a relativistic, gravitational, etc
redshift as a cosmological one.
Parameters
----------
cosmology : `~astropy.cosmology.Cosmology`, str, or None, optional
A cosmology realization or built-in cosmology's name (e.g. 'Planck18').
If None, will use the default cosmology
(controlled by :class:`~astropy.cosmology.default_cosmology`).
Tcmb : bool (optional, keyword-only)
Whether to create a CMB temperature <-> redshift equivalency, using
``Cosmology.Tcmb``. Default is False.
atzkw : dict or None (optional, keyword-only)
keyword arguments for :func:`~astropy.cosmology.z_at_value`
Returns
-------
`~astropy.units.equivalencies.Equivalency`
With equivalencies between redshift and temperature.
"""
from astropy.cosmology import default_cosmology, z_at_value
# get cosmology: None -> default and process str / class
cosmology = cosmology if cosmology is not None else default_cosmology.get()
with default_cosmology.set(cosmology): # if already cosmo, passes through
cosmology = default_cosmology.get()
atzkw = atzkw if atzkw is not None else {}
equivs = [] # will append as built
# -----------
# CMB Temperature <-> Redshift
if Tcmb:
equivs.extend(redshift_temperature(cosmology, **atzkw))
# -----------
return u.Equivalency(equivs, "with_redshift", {
'cosmology': cosmology,
'Tcmb': Tcmb
})
def test_hubble(self, cosmo):
"""Test Hubble equivalency component."""
unit = u.km / u.s / u.Mpc
default_cosmo = default_cosmology.get()
z = 15 * cu.redshift
H = cosmo.H(z)
h = H.to_value(u.km / u.s / u.Mpc) / 100 * cu.littleh
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.with_redshift(hubble=True)
# H
assert_quantity_allclose(z.to(unit, equivalency), H)
assert_quantity_allclose(H.to(cu.redshift, equivalency), z)
# little-h
assert_quantity_allclose(z.to(cu.littleh, equivalency), h)
assert_quantity_allclose(h.to(cu.redshift, equivalency), z)
# showing the answer changes if the cosmology changes
# this test uses the default cosmology
equivalency = cu.with_redshift(hubble=True)
assert_quantity_allclose(z.to(unit, equivalency), default_cosmo.H(z))
assert default_cosmo.H(z) != H
# 2) Specifying the cosmology
equivalency = cu.with_redshift(cosmo, hubble=True)
# H
assert_quantity_allclose(z.to(unit, equivalency), H)
assert_quantity_allclose(H.to(cu.redshift, equivalency), z)
# little-h
assert_quantity_allclose(z.to(cu.littleh, equivalency), h)
assert_quantity_allclose(h.to(cu.redshift, equivalency), z)
# Test `atzkw`
# this is really just a test that 'atzkw' doesn't fail
equivalency = cu.with_redshift(cosmo,
hubble=True,
atzkw={"ztol": 1e-10})
assert_quantity_allclose(H.to(cu.redshift, equivalency), z) # H
assert_quantity_allclose(h.to(cu.redshift, equivalency), z) # h
def test_redshift_hubble():
"""Test :func:`astropy.cosmology.units.redshift_hubble`."""
unit = u.km / u.s / u.Mpc
cosmo = Planck13.clone(H0=100 * unit)
default_cosmo = default_cosmology.get()
z = 15 * cu.redshift
H = cosmo.H(z)
h = H.to_value(u.km/u.s/u.Mpc) / 100 * cu.littleh
# 1) Default (without specifying the cosmology)
with default_cosmology.set(cosmo):
equivalency = cu.redshift_hubble()
# H
assert_quantity_allclose(z.to(unit, equivalency), H)
assert_quantity_allclose(H.to(cu.redshift, equivalency), z)
# little-h
assert_quantity_allclose(z.to(cu.littleh, equivalency), h)
assert_quantity_allclose(h.to(cu.redshift, equivalency), z)
# showing the answer changes if the cosmology changes
# this test uses the default cosmology
equivalency = cu.redshift_hubble()
assert_quantity_allclose(z.to(unit, equivalency), default_cosmo.H(z))
assert default_cosmo.H(z) != H
# 2) Specifying the cosmology
equivalency = cu.redshift_hubble(cosmo)
# H
assert_quantity_allclose(z.to(unit, equivalency), H)
assert_quantity_allclose(H.to(cu.redshift, equivalency), z)
# little-h
assert_quantity_allclose(z.to(cu.littleh, equivalency), h)
assert_quantity_allclose(h.to(cu.redshift, equivalency), z)
# Test `atzkw`
equivalency = cu.redshift_hubble(cosmo, ztol=1e-10)
assert_quantity_allclose(H.to(cu.redshift, equivalency), z) # H
assert_quantity_allclose(h.to(cu.redshift, equivalency), z) # little-h
def with_redshift(cosmology=None,
*,
distance="comoving",
hubble=True,
Tcmb=True,
atzkw=None):
"""Convert quantities between measures of cosmological distance.
Note: by default all equivalencies are on and must be explicitly turned off.
Care should be taken to not misinterpret a relativistic, gravitational, etc
redshift as a cosmological one.
Parameters
----------
cosmology : `~astropy.cosmology.Cosmology`, str, or None, optional
A cosmology realization or built-in cosmology's name (e.g. 'Planck18').
If `None`, will use the default cosmology
(controlled by :class:`~astropy.cosmology.default_cosmology`).
distance : {'comoving', 'lookback', 'luminosity'} or None (optional, keyword-only)
The type of distance equivalency to create or `None`.
Default is 'comoving'.
hubble : bool (optional, keyword-only)
Whether to create a Hubble parameter <-> redshift equivalency, using
``Cosmology.H``. Default is `True`.
Tcmb : bool (optional, keyword-only)
Whether to create a CMB temperature <-> redshift equivalency, using
``Cosmology.Tcmb``. Default is `True`.
atzkw : dict or None (optional, keyword-only)
keyword arguments for :func:`~astropy.cosmology.z_at_value`
Returns
-------
`~astropy.units.equivalencies.Equivalency`
With equivalencies between redshift and distance / Hubble / temperature.
Examples
--------
>>> import astropy.units as u
>>> import astropy.cosmology.units as cu
>>> from astropy.cosmology import WMAP9
>>> equivalency = cu.with_redshift(WMAP9)
>>> z = 1100 * cu.redshift
Redshift to (comoving) distance:
>>> z.to(u.Mpc, equivalency) # doctest: +FLOAT_CMP
<Quantity 14004.03157418 Mpc>
Redshift to the Hubble parameter:
>>> z.to(u.km / u.s / u.Mpc, equivalency) # doctest: +FLOAT_CMP
<Quantity 1565637.40154275 km / (Mpc s)>
>>> z.to(cu.littleh, equivalency) # doctest: +FLOAT_CMP
<Quantity 15656.37401543 littleh>
Redshift to CMB temperature:
>>> z.to(u.K, equivalency)
<Quantity 3000.225 K>
"""
from astropy.cosmology import default_cosmology, z_at_value
# get cosmology: None -> default and process str / class
cosmology = cosmology if cosmology is not None else default_cosmology.get()
with default_cosmology.set(cosmology): # if already cosmo, passes through
cosmology = default_cosmology.get()
atzkw = atzkw if atzkw is not None else {}
equivs = [] # will append as built
# Hubble <-> Redshift
if hubble:
equivs.extend(redshift_hubble(cosmology, **atzkw))
# CMB Temperature <-> Redshift
if Tcmb:
equivs.extend(redshift_temperature(cosmology, **atzkw))
# Distance <-> Redshift, but need to choose which distance
if distance is not None:
equivs.extend(redshift_distance(cosmology, kind=distance, **atzkw))
# -----------
return u.Equivalency(
equivs, "with_redshift", {
'cosmology': cosmology,
'distance': distance,
'hubble': hubble,
'Tcmb': Tcmb
})
def redshift_hubble(cosmology=None, **atzkw):
"""Convert quantities between redshift and Hubble parameter and little-h.
Care should be taken to not misinterpret a relativistic, gravitational, etc
redshift as a cosmological one.
Parameters
----------
cosmology : `~astropy.cosmology.Cosmology`, str, or None, optional
A cosmology realization or built-in cosmology's name (e.g. 'Planck18').
If None, will use the default cosmology
(controlled by :class:`~astropy.cosmology.default_cosmology`).
**atzkw
keyword arguments for :func:`~astropy.cosmology.z_at_value`
Returns
-------
`~astropy.units.equivalencies.Equivalency`
Equivalency between redshift and Hubble parameter and little-h unit.
Examples
--------
>>> import astropy.units as u
>>> import astropy.cosmology.units as cu
>>> from astropy.cosmology import WMAP9
>>> z = 1100 * cu.redshift
>>> equivalency = cu.redshift_hubble(WMAP9) # construct equivalency
>>> z.to(u.km / u.s / u.Mpc, equivalency) # doctest: +FLOAT_CMP
<Quantity 1565637.40154275 km / (Mpc s)>
>>> z.to(cu.littleh, equivalency) # doctest: +FLOAT_CMP
<Quantity 15656.37401543 littleh>
"""
from astropy.cosmology import default_cosmology, z_at_value
# get cosmology: None -> default and process str / class
cosmology = cosmology if cosmology is not None else default_cosmology.get()
with default_cosmology.set(cosmology): # if already cosmo, passes through
cosmology = default_cosmology.get()
def z_to_hubble(z):
"""Redshift to Hubble parameter."""
return cosmology.H(z)
def hubble_to_z(H):
"""Hubble parameter to redshift."""
return z_at_value(cosmology.H, H << (u.km / u.s / u.Mpc), **atzkw)
def z_to_littleh(z):
"""Redshift to :math:`h`-unit Quantity."""
return z_to_hubble(z).to_value(u.km / u.s / u.Mpc) / 100 * littleh
def littleh_to_z(h):
""":math:`h`-unit Quantity to redshift."""
return hubble_to_z(h * 100)
return u.Equivalency(
[(redshift, u.km / u.s / u.Mpc, z_to_hubble, hubble_to_z),
(redshift, littleh, z_to_littleh, littleh_to_z)], "redshift_hubble",
{'cosmology': cosmology})
