def test_write():
"""
Tests whether swiftsimio can handle a new particle type. If the test doesn't crash
this is a success.
"""
# Use default units, i.e. cm, grams, seconds, Ampere, Kelvin
unit_system = unyt.UnitSystem(name="default",
length_unit=unyt.cm,
mass_unit=unyt.g,
time_unit=unyt.s)
# Specify a new type in the metadata - currently done by editing the dictionaries directly.
# TODO: Remove this terrible way of setting up different particle types.
swp.particle_name_underscores[6] = "extratype"
swp.particle_name_class[6] = "Extratype"
swp.particle_name_text[6] = "Extratype"
swmw.extratype = {"smoothing_length": "SmoothingLength", **swmw.shared}
boxsize = 10 * unyt.cm
x = Writer(unit_system, boxsize, unit_fields_generate_units=generate_units)
x.extratype.coordinates = np.zeros((10, 3)) * unyt.cm
for i in range(0, 10):
x.extratype.coordinates[i][0] = float(i)
x.extratype.velocities = np.zeros((10, 3)) * unyt.cm / unyt.s
x.extratype.masses = np.ones(10, dtype=float) * unyt.g
x.extratype.smoothing_length = np.ones(10, dtype=float) * (5.0 * unyt.cm)
x.write("extra_test.hdf5")
# Clean up these global variables we screwed around with...
swp.particle_name_underscores.pop(6)
swp.particle_name_class.pop(6)
swp.particle_name_text.pop(6)
# generate the coordinates
dist = np.random.rand(num_part) * (max_r - min_r) + min_r
angle = np.random.rand(num_part) * 2 * np.pi
# more easy to do it in 2D, therefore coords[:, 2] == 0
coords = np.zeros((num_part, 3))
coords[:, 0] = dist * np.sin(angle)
coords[:, 1] = dist * np.cos(angle)
coords += boxsize * 0.5
# generate the masses
m = np.ones(num_part) * masses
# generate the velocities
sign = np.random.rand(num_part)
sign[sign < 0.5] = -1
sign[sign >= 0.5] = 1
v = np.zeros((num_part, 3))
v[:, 0] = sign * np.sqrt(G * M / (dist * (1 + np.tan(angle)**2)))
v[:, 1] = - np.tan(angle) * v[:, 0]
# Write the snapshot
units = unyt.UnitSystem("Planets", unyt.AU, unyt.mearth, unyt.yr)
snapshot = Writer(units, boxsize * unyt.AU)
snapshot.dark_matter.coordinates = coords * unyt.AU
snapshot.dark_matter.velocities = v * unyt.AU / unyt.yr
snapshot.dark_matter.masses = m * unyt.mearth
snapshot.write(filename)
"""
Contains unit systems that may be useful to astronomers. In particular,
it contains the cosmo_units which can be considered Gadget-oid default units,
with
+ Unit length = Mpc
+ Unit velocity = km/s
+ Unit mass = 10^10 Msun
+ Unit temperature = K
"""
import unyt
cosmo_units = unyt.UnitSystem(
"cosmological",
unyt.Mpc,
1e10 * unyt.msun,
(1.0 * unyt.s * unyt.Mpc / unyt.km).to(unyt.Gyr),
)
"""Define stress/strain tensors."""
from numpy import array, empty
import unyt as u
from unyt.array import unyt_array
# set unit regsitry
us_unit_system = u.UnitSystem(name='US',
length_unit='inch',
mass_unit='lb',
time_unit='s',
temperature_unit='degF',
angle_unit='deg')
# add strain unit
ureg = u.UnitRegistry()
ureg.add('strain',
base_value=1.0,
dimensions=u.dimensions.dimensionless,
tex_repr=r"\rm{\varepsilon}",
prefixable=True)
u.unit_registry.default_unit_registry = ureg
class Tensor(unyt_array):
"""Base 3x3 symmetric tensor.
Parameters
----------
matrix : numpy.array_like
an array-like object with six values
"""
Contains unit systems that may be useful to astronomers. In particular,
it contains the cosmo_units which can be considered Gadget-oid default units,
with
+ Unit length = Mpc
+ Unit velocity = km/s
+ Unit mass = 10^10 Msun
+ Unit temperature = K
"""
import unyt
cosmo_units = unyt.UnitSystem(
"cosmological", unyt.Mpc, 1e10 * unyt.msun, unyt.s * unyt.Mpc / unyt.km
)
"""Utility functions for handling units."""
import unyt as u
planckton_units = u.UnitSystem("planckton",
mass_unit="amu",
length_unit="nm",
time_unit="s")
planckton_units["energy"] = "kJ"
constants = {
"avogadro": 6.022140857e23 / u.mol,
"boltzmann": 1.38064852e-23 * u.J / u.K,
}
def quantity_to_tuple(quantity):
"""Break a unyt.quantity into a tuple.
Convert a unyt.quantity into a tuple containing its value and units in
string format. Useful for serialization.
IMPORTANT: This function expects one quantity, not an array.
Parameters
----------
quantity: unyt.unyt_quantity
Returns
-------
(number, string)
"""
from pygadgetreader import *
from swiftsimio import Writer
import numpy as np
import unyt
filename = "/cosma7/data/dp004/jlvc76/nIFTy/IC_CLUSTER_00019"
length = unyt.kpc
mass = 1e10 * unyt.msun
time = (1.0 * unyt.s * unyt.kpc / unyt.km).to("s")
velocity = length / time
energy_per_unit_mass = (length / time)**2
nifty_units = unyt.UnitSystem("nifty", 1e3 * length, mass, time)
writer = Writer(
unit_system=nifty_units,
box_size=readheader(filename, "boxsize") * length,
dimension=3,
compress=True,
extra_header={
"Redshift": readheader(filename, "redshift"),
"Omega0": readheader(filename, "O0"),
"OmegaLambda": readheader(filename, "Ol"),
"HubbleParam": readheader(filename, "h"),
},
)
writer.gas.coordinates = unyt.unyt_array(readsnap(filename, "pos", 0), length)
def create_unit_system(length: UnitLike,
mass: UnitLike,
time: UnitLike,
temperature: UnitLike = None,
angle: UnitLike = None,
current_mks: UnitLike = None,
luminous_intensity: UnitLike = None,
logarithmic: UnitLike = None,
name: str = None,
registry: t.Optional[unyt.UnitRegistry] = None,
consistent: bool = False,
strict_dims: bool = True,
**convenience_units: UnitLike) -> unyt.UnitSystem:
"""
Create a new unit system.
Parameters
----------
length : UnitLike
The base length unit.
mass : UnitLike
The base mass unit.
time : UnitLike
The base time unit.
temperature : UnitLike, optional
The base temperature unit. (default: 'K')
angle : UnitLike, optional
The base angle unit. (default: 'rad')
current_mks : UnitLike, optional
The base current unit. (default: 'A')
luminous_intensity : UnitLike, optional
The base luminous intensity unit. (default: 'Cd')
logarithmic : UnitLike, optional
The base logarithmic unit. (default: 'Np')
name : str, optional
Name for the unit system. If not provided, a name is generated from the
provided base units. (default: None)
registry : UnitRegistry, optional
The unit registry for the system. If None, the default unit registry is
used.
consistent : bool, optional
If True, enforce consistency between convenience units and base units
such that, in base units, convenience units have a magnitude of 1.0. For
example, force='N' is consistent with MKS (N = 1.0 kg*m/s**2), but
force='kN' is not (kN = 1e3 kg*m/s**2). (default: False)
strict_dims : bool, optional
If True, strictly enforce convenience units having the dimensions they
map to. (default: True)
**convenience_units : str, optional
Mapping of dimension names to convenience units, e.g., ``force='kN'``.
Raises
------
IllDefinedUnitSystem
If `strict_dims` is True and convenience units do not strictly map
UnitSystemExistsError
If a unit system with name `name` already exists
UnitSystemConsistencyError
If `consistent` is True and unit system is not consistent
Example
-------
Unit system that uses millimeters and gigagrams, with a convenience
kilonewton unit:
>>> system = create_unit_system('mm', 'Gg', 's', force='kN')
>>> system
mm_Gg_s Unit System
Base Units:
length: mm
mass: Gg
time: s
temperature: K
angle: rad
current_mks: A
luminous_intensity: cd
logarithmic: Np
Other Units:
force: kN
Unit system with different base temperature unit, but still auto-generated
name:
>>> system = create_unit_system('m', 'kg', 's', temperature='degC')
>>> system
m_kg_s_degC Unit System
Base Units:
length: m
mass: kg
time: s
temperature: degC
angle: rad
current_mks: A
luminous_intensity: cd
logarithmic: Np
Other Units:
"""
base_units = dict(length_unit=length, mass_unit=mass, time_unit=time)
# Handle other default base units; don't include them in auto-generated name
# if not provided. They already have defaults set by the UnitSystem
# constructor.
if temperature is not None:
base_units['temperature_unit'] = temperature
if angle is not None:
base_units['angle_unit'] = angle
if current_mks is not None:
base_units['current_mks_unit'] = current_mks
if luminous_intensity is not None:
base_units['luminous_intensity_unit'] = luminous_intensity
if logarithmic is not None:
base_units['logarithmic_unit'] = logarithmic
# Generate name if not provided.
if name is None:
name = '_'.join(map(str, base_units.values()))
# Check against existing unit systems.
if name in unyt.unit_systems.unit_system_registry:
raise UnitSystemExistsError(name)
if registry is None:
registry = unyt.unit_registry.default_unit_registry
# Create new system with base units.
system = unyt.UnitSystem(str(name), **base_units, registry=registry)
try:
# Apply convenience units.
for dim, unit in convenience_units.items():
if strict_dims:
dim_obj = getattr(unyt.dimensions, dim)
unit_obj = unyt.Unit(unit)
if unit_obj.dimensions != dim_obj:
raise IllDefinedUnitSystem(
f'{dim} [{dim_obj}] -> {unit_obj} '
f'[{unit_obj.dimensions}]')
system[dim] = unit
# Check consistency if asked to.
if consistent:
check = check_consistent_unit_system(system)
if not check.is_consistent:
raise UnitSystemConsistencyError(
f'Inconsistent unit for dimension {check.bad_dim!r}: '
f'1.0 {check.bad_unit} = {check.bad_base}')
except:
# Remove bad system from registry
del unyt.unit_systems.unit_system_registry[name]
raise
return system
"""
Contains unit systems that may be useful to astronomers. In particular,
it contains the cosmo_units which can be considered Gadget-oid default units,
with
+ Unit length = Mpc
+ Unit velocity = km/s
+ Unit mass = 10^10 Msun
+ Unit temperature = K
Also contains unit conversion factors, to simplify units wherever possible.
"""
import unyt
try:
# Need to do this first otherwise the `unyt` system freaks out about
# us upgrading msun from a symbol
cosmo_units = unyt.UnitSystem(
"cosmological",
unyt.Mpc,
unyt.unyt_quantity(1e10, units=unyt.Solar_Mass),
unyt.unyt_quantity(1.0,
units=unyt.s * unyt.Mpc / unyt.km).to(unyt.Gyr),
)
except RuntimeError:
# We've already done that, oops.
cosmo_units = unyt.unit_systems.cosmological
pass
