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OpenMC/openmc/weight_windows.py
Patrick Myers 1cb22075ef
Changed xml to lxml (#2489)
2023-05-09 10:41:04 -05:00

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from __future__ import annotations
from collections.abc import Iterable
from numbers import Real, Integral
import pathlib
import typing
from typing import Iterable, List, Optional, Union, Dict
import lxml.etree as ET
import numpy as np
import h5py
from openmc.filter import _PARTICLES
from openmc.mesh import MeshBase, RectilinearMesh, UnstructuredMesh
import openmc.checkvalue as cv
from openmc.checkvalue import PathLike
from ._xml import get_text
from .mixin import IDManagerMixin
class WeightWindows(IDManagerMixin):
"""Mesh-based weight windows
This class enables you to specify weight window parameters that are used in
a simulation. Multiple sets of weight windows can be defined for different
meshes and different particles. An iterable of :class:`WeightWindows`
instances can be assigned to the :attr:`openmc.Settings.weight_windows`
attribute, which is then exported to XML.
Weight window lower/upper bounds are to be specified for each combination of
a mesh element and an energy bin. Thus the total number of bounds should be
equal to the product of the number of mesh bins and the number of energy
bins.
.. versionadded:: 0.13
Parameters
----------
mesh : openmc.MeshBase
Mesh for the weight windows
lower_ww_bounds : Iterable of Real
A list of values for which each value is the lower bound of a weight
window
upper_ww_bounds : Iterable of Real
A list of values for which each value is the upper bound of a weight
window
upper_bound_ratio : float
Ratio of the lower to upper weight window bounds
energy_bounds : Iterable of Real
A list of values for which each successive pair constitutes a range of
energies in [eV] for a single bin
particle_type : {'neutron', 'photon'}
Particle type the weight windows apply to
survival_ratio : float
Ratio of the survival weight to the lower weight window bound for
rouletting
max_lower_bound_ratio : float
Maximum allowed ratio of a particle's weight to the weight window's
lower bound. A factor will be applied to raise the weight window to be
lower than the particle's weight by a factor of max_lower_bound_ratio
during transport if exceeded.
max_split : int
Maximum allowable number of particles when splitting
weight_cutoff : float
Threshold below which particles will be terminated
id : int
Unique identifier for the weight window settings. If not specified, an
identifier will automatically be assigned.
Attributes
----------
id : int
Unique identifier for the weight window settings.
mesh : openmc.MeshBase
Mesh for the weight windows with dimension (ni, nj, nk)
particle_type : str
Particle type the weight windows apply to
energy_bounds : Iterable of Real
A list of values for which each successive pair constitutes a range of
energies in [eV] for a single bin
num_energy_bins : int
Number of energy bins
lower_ww_bounds : numpy.ndarray of float
An array of values for which each value is the lower bound of a weight
window. Shape: (ni, nj, nk, num_energy_bins) for StructuredMesh;
(num_elements, num_energy_bins) for UnstructuredMesh
upper_ww_bounds : numpy.ndarray of float
An array of values for which each value is the upper bound of a weight
window. Shape: (ni, nj, nk, num_energy_bins) for StructuredMesh;
(num_elements, num_energy_bins) for UnstructuredMesh
survival_ratio : float
Ratio of the survival weight to the lower weight window bound for
rouletting
max_lower_bound_ratio: float
Maximum allowed ratio of a particle's weight to the weight window's
lower bound. (Default: 1.0)
max_split : int
Maximum allowable number of particles when splitting
weight_cutoff : float
Threshold below which particles will be terminated
See Also
--------
openmc.Settings
"""
next_id = 1
used_ids = set()
def __init__(
self,
mesh: MeshBase,
lower_ww_bounds: Iterable[float],
upper_ww_bounds: Optional[Iterable[float]] = None,
upper_bound_ratio: Optional[float] = None,
energy_bounds: Optional[Iterable[Real]] = None,
particle_type: str = 'neutron',
survival_ratio: float = 3,
max_lower_bound_ratio: Optional[float] = None,
max_split: int = 10,
weight_cutoff: float = 1.e-38,
id: Optional[int] = None
):
self.mesh = mesh
self.id = id
self.particle_type = particle_type
self.energy_bounds = energy_bounds
self.lower_ww_bounds = lower_ww_bounds
if upper_ww_bounds is not None and upper_bound_ratio:
raise ValueError("Exactly one of upper_ww_bounds and "
"upper_bound_ratio must be present.")
if upper_ww_bounds is None and upper_bound_ratio is None:
raise ValueError("Exactly one of upper_ww_bounds and "
"upper_bound_ratio must be present.")
if upper_bound_ratio:
self.upper_ww_bounds = [
lb * upper_bound_ratio for lb in self.lower_ww_bounds
]
if upper_ww_bounds is not None:
self.upper_ww_bounds = upper_ww_bounds
if len(self.lower_ww_bounds) != len(self.upper_ww_bounds):
raise ValueError('Size of the lower and upper weight '
'window bounds do not match')
self.survival_ratio = survival_ratio
self._max_lower_bound_ratio = None
if max_lower_bound_ratio is not None:
self.max_lower_bound_ratio = max_lower_bound_ratio
self.max_split = max_split
self.weight_cutoff = weight_cutoff
def __repr__(self) -> str:
string = type(self).__name__ + '\n'
string += '{: <16}=\t{}\n'.format('\tID', self._id)
string += '{: <16}=\t{}\n'.format('\tMesh:', self.mesh)
string += '{: <16}=\t{}\n'.format('\tParticle Type', self._particle_type)
string += '{: <16}=\t{}\n'.format('\tEnergy Bounds', self._energy_bounds)
string += '{: <16}=\t{}\n'.format('\tLower WW Bounds', self._lower_ww_bounds)
string += '{: <16}=\t{}\n'.format('\tUpper WW Bounds', self._upper_ww_bounds)
string += '{: <16}=\t{}\n'.format('\tSurvival Ratio', self._survival_ratio)
string += '{: <16}=\t{}\n'.format('\tMax Split', self._max_split)
string += '{: <16}=\t{}\n'.format('\tWeight Cutoff', self._weight_cutoff)
return string
def __eq__(self, other: WeightWindows) -> bool:
# ensure that `other` is a WeightWindows object
if not isinstance(other, WeightWindows):
return False
# TODO: add ability to check mesh equality
# check several attributes directly
attrs = ('particle_type',
'survival_ratio',
'max_lower_bound_ratio',
'max_split',
'weight_cutoff')
for attr in attrs:
if getattr(self, attr) != getattr(other, attr):
return False
# save most expensive checks for last
if not np.array_equal(self.energy_bounds, other.energy_bounds):
return False
if not np.array_equal(self.lower_ww_bounds, other.lower_ww_bounds):
return False
if not np.array_equal(self.upper_ww_bounds, other.upper_ww_bounds):
return False
return True
@property
def mesh(self) -> MeshBase:
return self._mesh
@mesh.setter
def mesh(self, mesh: MeshBase):
cv.check_type('Weight window mesh', mesh, MeshBase)
self._mesh = mesh
@property
def particle_type(self) -> str:
return self._particle_type
@particle_type.setter
def particle_type(self, pt: str):
cv.check_value('Particle type', pt, _PARTICLES)
self._particle_type = pt
@property
def energy_bounds(self) -> Iterable[Real]:
return self._energy_bounds
@energy_bounds.setter
def energy_bounds(self, bounds: Iterable[float]):
cv.check_type('Energy bounds', bounds, Iterable, Real)
self._energy_bounds = np.asarray(bounds)
@property
def num_energy_bins(self) -> int:
if self.energy_bounds is None:
raise ValueError('Energy bounds are not set')
return self.energy_bounds.size - 1
@property
def lower_ww_bounds(self) -> np.ndarray:
return self._lower_ww_bounds
@lower_ww_bounds.setter
def lower_ww_bounds(self, bounds: Iterable[float]):
cv.check_iterable_type('Lower WW bounds',
bounds,
Real,
min_depth=1,
max_depth=4)
# reshape data according to mesh and energy bins
bounds = np.asarray(bounds)
if isinstance(self.mesh, UnstructuredMesh):
bounds = bounds.reshape(-1, self.num_energy_bins)
else:
bounds = bounds.reshape(*self.mesh.dimension, self.num_energy_bins)
self._lower_ww_bounds = bounds
@property
def upper_ww_bounds(self) -> np.ndarray:
return self._upper_ww_bounds
@upper_ww_bounds.setter
def upper_ww_bounds(self, bounds: Iterable[float]):
cv.check_iterable_type('Upper WW bounds',
bounds,
Real,
min_depth=1,
max_depth=4)
# reshape data according to mesh and energy bins
bounds = np.asarray(bounds)
if isinstance(self.mesh, UnstructuredMesh):
bounds = bounds.reshape(-1, self.num_energy_bins)
else:
bounds = bounds.reshape(*self.mesh.dimension, self.num_energy_bins)
self._upper_ww_bounds = bounds
@property
def survival_ratio(self) -> float:
return self._survival_ratio
@survival_ratio.setter
def survival_ratio(self, val: float):
cv.check_type('Survival ratio', val, Real)
cv.check_greater_than('Survival ratio', val, 1.0, True)
self._survival_ratio = val
@property
def max_lower_bound_ratio(self) -> float:
return self._max_lower_bound_ratio
@max_lower_bound_ratio.setter
def max_lower_bound_ratio(self, val: float):
cv.check_type('Maximum lower bound ratio', val, Real)
cv.check_greater_than('Maximum lower bound ratio', val, 1.0)
self._max_lower_bound_ratio = val
@property
def max_split(self) -> int:
return self._max_split
@max_split.setter
def max_split(self, val: int):
cv.check_type('Max split', val, Integral)
self._max_split = val
@property
def weight_cutoff(self) -> float:
return self._weight_cutoff
@weight_cutoff.setter
def weight_cutoff(self, cutoff: float):
cv.check_type('Weight cutoff', cutoff, Real)
cv.check_greater_than('Weight cutoff', cutoff, 0.0, True)
self._weight_cutoff = cutoff
def to_xml_element(self) -> ET.Element:
"""Return an XML representation of the weight window settings
Returns
-------
element : lxml.etree._Element
XML element containing the weight window information
"""
element = ET.Element('weight_windows')
element.set('id', str(self._id))
subelement = ET.SubElement(element, 'mesh')
subelement.text = str(self.mesh.id)
subelement = ET.SubElement(element, 'particle_type')
subelement.text = self.particle_type
subelement = ET.SubElement(element, 'energy_bounds')
subelement.text = ' '.join(str(e) for e in self.energy_bounds)
subelement = ET.SubElement(element, 'lower_ww_bounds')
subelement.text = ' '.join(str(b) for b in self.lower_ww_bounds.ravel('F'))
subelement = ET.SubElement(element, 'upper_ww_bounds')
subelement.text = ' '.join(str(b) for b in self.upper_ww_bounds.ravel('F'))
subelement = ET.SubElement(element, 'survival_ratio')
subelement.text = str(self.survival_ratio)
if self.max_lower_bound_ratio is not None:
subelement = ET.SubElement(element, 'max_lower_bound_ratio')
subelement.text = str(self.max_lower_bound_ratio)
subelement = ET.SubElement(element, 'max_split')
subelement.text = str(self.max_split)
subelement = ET.SubElement(element, 'weight_cutoff')
subelement.text = str(self.weight_cutoff)
return element
@classmethod
def from_xml_element(cls, elem: ET.Element, root: ET.Element) -> WeightWindows:
"""Generate weight window settings from an XML element
Parameters
----------
elem : lxml.etree._Element
XML element
root : lxml.etree._Element
Root element for the file where meshes can be found
Returns
-------
openmc.WeightWindows
Weight windows object
"""
# Get mesh for weight windows
mesh_id = int(get_text(elem, 'mesh'))
path = f"./mesh[@id='{mesh_id}']"
mesh_elem = root.find(path)
if mesh_elem is not None:
mesh = MeshBase.from_xml_element(mesh_elem)
# Read all other parameters
lower_ww_bounds = [float(l) for l in get_text(elem, 'lower_ww_bounds').split()]
upper_ww_bounds = [float(u) for u in get_text(elem, 'upper_ww_bounds').split()]
e_bounds = [float(b) for b in get_text(elem, 'energy_bounds').split()]
particle_type = get_text(elem, 'particle_type')
survival_ratio = float(get_text(elem, 'survival_ratio'))
ww_shape = (len(e_bounds) - 1,) + mesh.dimension[::-1]
lower_ww_bounds = np.array(lower_ww_bounds).reshape(ww_shape).T
upper_ww_bounds = np.array(upper_ww_bounds).reshape(ww_shape).T
max_lower_bound_ratio = None
if get_text(elem, 'max_lower_bound_ratio'):
max_lower_bound_ratio = float(get_text(elem, 'max_lower_bound_ratio'))
max_split = int(get_text(elem, 'max_split'))
weight_cutoff = float(get_text(elem, 'weight_cutoff'))
id = int(get_text(elem, 'id'))
return cls(
mesh=mesh,
lower_ww_bounds=lower_ww_bounds,
upper_ww_bounds=upper_ww_bounds,
energy_bounds=e_bounds,
particle_type=particle_type,
survival_ratio=survival_ratio,
max_lower_bound_ratio=max_lower_bound_ratio,
max_split=max_split,
weight_cutoff=weight_cutoff,
id=id
)
@classmethod
def from_hdf5(cls, group: h5py.Group, meshes: Dict[int, MeshBase]) -> WeightWindows:
"""Create weight windows from HDF5 group
Parameters
----------
group : h5py.Group
Group in HDF5 file
meshes : dict
Dictionary mapping IDs to mesh objects
Returns
-------
openmc.WeightWindows
A weight window object
"""
id = int(group.name.split('/')[-1].lstrip('weight_windows'))
mesh_id = group['mesh'][()]
ptype = group['particle_type'][()].decode()
e_bounds = group['energy_bounds'][()]
lower_ww_bounds = group['lower_ww_bounds'][()]
upper_ww_bounds = group['upper_ww_bounds'][()]
survival_ratio = group['survival_ratio'][()]
max_lower_bound_ratio = None
if group.get('max_lower_bound_ratio') is not None:
max_lower_bound_ratio = group['max_lower_bound_ratio'][()]
max_split = group['max_split'][()]
weight_cutoff = group['weight_cutoff'][()]
return cls(
mesh=meshes[mesh_id],
lower_ww_bounds=lower_ww_bounds,
upper_ww_bounds=upper_ww_bounds,
energy_bounds=e_bounds,
particle_type=ptype,
survival_ratio=survival_ratio,
max_lower_bound_ratio=max_lower_bound_ratio,
max_split=max_split,
weight_cutoff=weight_cutoff,
id=id
)
def wwinp_to_wws(path: PathLike) -> List[WeightWindows]:
"""Create WeightWindows instances from a wwinp file
.. versionadded:: 0.13.1
Parameters
----------
path : str or pathlib.Path
Path to the wwinp file
Returns
-------
list of openmc.WeightWindows
"""
with open(path) as wwinp:
# BLOCK 1
header = wwinp.readline().split(None, 4)
# read file type, time-dependence, number of
# particles, mesh type and problem identifier
_if, iv, ni, nr = [int(x) for x in header[:4]]
probid = header[4] if len(header) > 4 else ""
# header value checks
if _if != 1:
raise ValueError(f'Found incorrect file type, if: {_if}')
if iv > 1:
# read number of time bins for each particle, 'nt(1...ni)'
nt = np.fromstring(wwinp.readline(), sep=' ', dtype=int)
# raise error if time bins are present for now
raise ValueError('Time-dependent weight windows '
'are not yet supported')
else:
nt = ni * [1]
if nr == 16:
raise NotImplementedError('Cylindrical and spherical mesh '
'types are not yet supported')
# read number of energy bins for each particle, 'ne(1...ni)'
ne = np.fromstring(wwinp.readline(), sep=' ', dtype=int)
# read coarse mesh dimensions and lower left corner
mesh_description = np.fromstring(wwinp.readline(), sep=' ')
nfx, nfy, nfz = mesh_description[:3].astype(int)
xyz0 = mesh_description[3:]
# read cylindrical and spherical mesh vectors if present
if nr == 16:
# read number of coarse bins
line_arr = np.fromstring(wwinp.readline(), sep=' ')
ncx, ncy, ncz = line_arr[:3].astype(int)
# read polar vector (x1, y1, z1)
xyz1 = line_arr[3:] - xyz0
polar_vec = xyz1 / np.linalg.norm(xyz1)
# read azimuthal vector (x2, y2, z2)
line_arr = np.fromstring(wwinp.readline(), sep=' ')
xyz2 = line_arr[:3] - xyz0
azimuthal_vec = xyz2 / np.linalg.norm(xyz2)
# read geometry type
nwg = int(line_arr[-1])
elif nr == 10:
# read rectilinear data:
# number of coarse mesh bins and mesh type
ncx, ncy, ncz, nwg = \
np.fromstring(wwinp.readline(), sep=' ').astype(int)
else:
raise RuntimeError(f'Invalid mesh description (nr) found: {nr}')
# read BLOCK 2 and BLOCK 3 data into a single array
ww_data = np.fromstring(wwinp.read(), sep=' ')
# extract mesh data from the ww_data array
start_idx = 0
# first values in the mesh definition arrays are the first
# coordinate of the grid
end_idx = start_idx + 1 + 3 * ncx
x0, x_vals = ww_data[start_idx], ww_data[start_idx+1:end_idx]
start_idx = end_idx
end_idx = start_idx + 1 + 3 * ncy
y0, y_vals = ww_data[start_idx], ww_data[start_idx+1:end_idx]
start_idx = end_idx
end_idx = start_idx + 1 + 3 * ncz
z0, z_vals = ww_data[start_idx], ww_data[start_idx+1:end_idx]
start_idx = end_idx
# mesh consistency checks
if nr == 16 and nwg == 1:
raise ValueError(f'Mesh description in header ({nr}) '
f'does not match the mesh type ({nwg})')
if (xyz0 != (x0, y0, z0)).any():
raise ValueError(f'Mesh origin in the header ({xyz0}) '
f' does not match the origin in the mesh '
f' description ({x0, y0, z0})')
# create openmc mesh object
grids = []
mesh_definition = [(x0, x_vals, nfx), (y0, y_vals, nfy), (z0, z_vals, nfz)]
for grid0, grid_vals, n_pnts in mesh_definition:
# file spec checks for the mesh definition
if (grid_vals[2::3] != 1.0).any():
raise ValueError('One or more mesh ratio value, qx, '
'is not equal to one')
if grid_vals[::3].sum() != n_pnts:
raise ValueError('Sum of the fine bin entries, s, does '
'not match the number of fine bins')
# extend the grid based on the next coarse bin endpoint, px
# and the number of fine bins in the coarse bin, sx
intervals = grid_vals.reshape(-1, 3)
coords = [grid0]
for sx, px, qx in intervals:
coords += np.linspace(coords[-1], px, int(sx + 1)).tolist()[1:]
grids.append(np.array(coords))
mesh = RectilinearMesh()
mesh.x_grid, mesh.y_grid, mesh.z_grid = grids
# extract weight window values from array
wws = []
for ne_i, nt_i, particle_type in zip(ne, nt, ('neutron', 'photon')):
# no information to read for this particle if
# either the energy bins or time bins are empty
if ne_i == 0 or nt_i == 0:
continue
if iv > 1:
# time bins are parsed but unused for now
end_idx = start_idx + nt_i
time_bounds = ww_data[start_idx:end_idx]
np.insert(time_bounds, (0,), (0.0,))
start_idx = end_idx
# read energy boundaries
end_idx = start_idx + ne_i
energy_bounds = np.insert(ww_data[start_idx:end_idx], (0,), (0.0,))
# convert from MeV to eV
energy_bounds *= 1e6
start_idx = end_idx
# read weight window values
end_idx = start_idx + (nfx * nfy * nfz) * nt_i * ne_i
# read values and reshape according to ordering
# slowest to fastest: t, e, z, y, x
# reorder with transpose since our ordering is x, y, z, e, t
ww_shape = (nt_i, ne_i, nfz, nfy, nfx)
ww_values = ww_data[start_idx:end_idx].reshape(ww_shape).T
# Only use first time bin since we don't support time dependent weight
# windows yet.
ww_values = ww_values[:, :, :, :, 0]
start_idx = end_idx
# create a weight window object
ww = WeightWindows(id=None,
mesh=mesh,
lower_ww_bounds=ww_values,
upper_bound_ratio=5.0,
energy_bounds=energy_bounds,
particle_type=particle_type)
wws.append(ww)
return wws
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