"""
Python interface to read Les Houches Event (LHE) files.
"""
import gzip
import io
import os
import warnings
import xml.etree.ElementTree as ET
from collections.abc import Iterable, Iterator
from copy import deepcopy
from dataclasses import dataclass, field
from typing import (
Any,
BinaryIO,
Optional,
Protocol,
TextIO,
TypeVar,
Union,
)
from xml.sax.saxutils import quoteattr
import graphviz # type: ignore[import-untyped]
from particle import latex_to_html_name
from particle.converters.bimap import DirectionalMaps
from particle.exceptions import MatchingIDNotFound
from pylhe._version import version as __version__
__all__ = [
"LHEEvent",
"LHEEventInfo",
"LHEFile",
"LHEGenerator",
"LHEHeader",
"LHEInit",
"LHEInitInfo",
"LHEInitRWGTWeight",
"LHEInitRWGTWeightGroup",
"LHEParticle",
"LHEProcInfo",
"__version__",
"to_awkward",
]
def __dir__() -> list[str]:
return __all__
# retrieve mapping of PDG ID to particle name as LaTeX string
_PDGID2LaTeXNameMap, _ = DirectionalMaps("PDGID", "LATEXNAME", converters=(str, str))
PathLike = Union[str, bytes, os.PathLike[str], os.PathLike[bytes]]
class Writeable(Protocol):
"""
A protocol for writeable objects.
"""
def write(self, s: str) -> Any: # pragma: no cover
"""Write a string to the object."""
...
TWriteable = TypeVar("TWriteable", bound=Writeable)
def _open_xml_tag(tag: str, attributes: dict[str, str]) -> str:
"""Helper function to open an XML tag with attributes."""
attrs = ""
for k, v in attributes.items():
attrs += f" {k}={quoteattr(v)}"
return f"<{tag}{attrs}>"
def _copy_xml_element(element: ET.Element) -> ET.Element:
"""Return a detached copy of an XML element."""
copied = deepcopy(element)
copied.tail = None
return copied
[docs]
@dataclass
class LHEEventInfo:
"""
Store the event information in the LHE format.
"""
nparticles: int
"""Number of particles in the event"""
pid: int
"""Process ID for the event"""
weight: float
"""Event weight"""
scale: float
"""Energy scale of the event"""
aqed: float
"""QED coupling constant alpha_QED"""
aqcd: float
"""QCD coupling constant alpha_QCD"""
[docs]
def tolhe(self) -> str:
"""
Return the event info as a string in LHE format.
Returns:
str: The event info as a string in LHE format.
"""
return f"{self.nparticles:3d} {self.pid:6d} {self.weight: 15.10e} {self.scale: 15.10e} {self.aqed: 15.10e} {self.aqcd: 15.10e}"
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEEventInfo":
"""
Create an `LHEEventInfo` instance from a string in LHE format.
"""
values = string.split()
return cls(
nparticles=int(float(values[0])),
pid=int(float(values[1])),
weight=float(values[2]),
scale=float(values[3]),
aqed=float(values[4]),
aqcd=float(values[5]),
)
[docs]
@dataclass
class LHEParticle:
"""
Represents a single particle in the LHE format.
"""
id: int
"""PDG ID of the particle"""
status: int
"""Status code of the particle"""
mother1: int
"""First mother particle ID"""
mother2: int
"""Second mother particle ID"""
color1: int
"""First color line ID"""
color2: int
"""Second color line ID"""
px: float
"""Momentum x coordinate of the particle"""
py: float
"""Momentum y coordinate of the particle"""
pz: float
"""Momentum z coordinate of the particle"""
e: float
"""Energy of the particle"""
m: float
"""Mass of the particle"""
lifetime: float
"""Lifetime of the particle"""
spin: float
"""Spin of the particle"""
def __post_init__(self) -> None:
"""Initialize the event reference."""
# we store the circular event reference in a private attribute
self._event: Optional[LHEEvent] = None
@property
def event(self) -> Optional["LHEEvent"]:
"""
Reference to the parent event, set when the particle is added to an event.
.. deprecated:: 2.0.0
Access by `particle.event` is deprecated and will be removed in a future version.
"""
warnings.warn(
"Access by `particle.event` is deprecated and will be removed in a future version.",
DeprecationWarning,
stacklevel=2,
)
# Previously it was just event so we still allow that for backward compatibility
return self._event
@event.setter
def event(self, value: Optional["LHEEvent"]) -> None:
"""Set the parent event reference."""
# Previously it was just event so we still allow that for backward compatibility
self._event = value
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEParticle":
"""
Create an `LHEParticle` instance from a string in LHE format.
"""
values = string.split()
return cls(
id=int(float(values[0])),
status=int(float(values[1])),
mother1=int(float(values[2])),
mother2=int(float(values[3])),
color1=int(float(values[4])),
color2=int(float(values[5])),
px=float(values[6]),
py=float(values[7]),
pz=float(values[8]),
e=float(values[9]),
m=float(values[10]),
lifetime=float(values[11]),
spin=float(values[12]),
)
[docs]
def tolhe(self) -> str:
"""
Return the particle as a string in LHE format.
Returns:
str: The particle as a string in LHE format.
"""
return f"{self.id:5d} {self.status:3d} {self.mother1:3d} {self.mother2:3d} {self.color1:3d} {self.color2:3d} {self.px: 15.8e} {self.py: 15.8e} {self.pz: 15.8e} {self.e: 15.8e} {self.m: 15.8e} {self.lifetime: 10.4e} {self.spin: 10.4e}"
[docs]
def mothers(self) -> list["LHEParticle"]:
"""
Return a list of the particle's mothers.
.. deprecated:: 2.0.0
Accessing mothers via `LHEParticle.mothers()` is deprecated and will be removed in a future version. Use `LHEEvent.mothers(LHEParticle)` method, `LHEParticle.mother1` and `LHEParticle.mother2` instead.
"""
warnings.warn(
"Access by `LHEParticle.mothers()` is deprecated and will be removed in a future version. "
"Use `LHEEvent.mothers(LHEParticle)` method, `LHEParticle.mother1` and `LHEParticle.mother2` instead.",
DeprecationWarning,
stacklevel=2,
)
if self.event is None:
err = "Particle is not associated to an event."
raise ValueError(err)
first_idx = int(self.mother1) - 1
second_idx = int(self.mother2) - 1
return [
self.event.particles[idx] for idx in (first_idx, second_idx) if idx >= 0
]
def _indent(elem: ET.Element, level: int = 0) -> None:
"""
XML indentation helper from https://stackoverflow.com/a/33956544.
"""
i = "\n" + level * " "
if len(elem):
if not elem.text or not elem.text.strip():
elem.text = i + " "
if not elem.tail or not elem.tail.strip():
elem.tail = i
for inner_elem in elem:
_indent(inner_elem, level + 1)
elem = inner_elem
if not elem.tail or not elem.tail.strip():
elem.tail = i
elif level and (not elem.tail or not elem.tail.strip()):
elem.tail = i
[docs]
@dataclass
class LHEInitInfo:
"""Store the first line of the <init> block as a dataclass."""
beamA: int
"""Beam A PDG ID"""
beamB: int
"""Beam B PDG ID"""
energyA: float
"""Beam A energy"""
energyB: float
"""Beam B energy"""
PDFgroupA: int
"""PDF group for beam A"""
PDFgroupB: int
"""PDF group for beam B"""
PDFsetA: int
"""PDF set for beam A"""
PDFsetB: int
"""PDF set for beam B"""
weightingStrategy: int
"""Weighting strategy"""
numProcesses: int
"""Number of processes"""
[docs]
def tolhe(self) -> str:
"""
Return the init info block as a string in LHE format.
Returns:
str: The init info block as a string in LHE format.
"""
return f" {self.beamA: 6d} {self.beamB: 6d} {self.energyA: 14.7e} {self.energyB: 14.7e} {self.PDFgroupA: 5d} {self.PDFgroupB: 5d} {self.PDFsetA: 5d} {self.PDFsetB: 5d} {self.weightingStrategy: 5d} {self.numProcesses: 5d}"
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEInitInfo":
"""
Create an `LHEInitInfo` instance from a string in LHE format.
"""
values = string.split()
return cls(
beamA=int(float(values[0])),
beamB=int(float(values[1])),
energyA=float(values[2]),
energyB=float(values[3]),
PDFgroupA=int(float(values[4])),
PDFgroupB=int(float(values[5])),
PDFsetA=int(float(values[6])),
PDFsetB=int(float(values[7])),
weightingStrategy=int(float(values[8])),
numProcesses=int(float(values[9])),
)
[docs]
@dataclass
class LHEProcInfo:
"""Store the process info block as a dataclass."""
xSection: float
"""Cross section of the process"""
error: float
"""Uncertainty/error of the cross section"""
unitWeight: float
"""Unit weight of the process"""
procId: int
"""Process ID"""
[docs]
def tolhe(self) -> str:
"""
Return the process info block as a string in LHE format.
Returns:
str: The process info block as a string in LHE format.
"""
return f"{self.xSection: 14.7e} {self.error: 14.7e} {self.unitWeight: 14.7e} {self.procId: 5d}"
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEProcInfo":
"""
Create an `LHEProcInfo` instance from a string in LHE format.
"""
values = string.split()
return cls(
xSection=float(values[0]),
error=float(values[1]),
unitWeight=float(values[2]),
procId=int(float(values[3])),
)
[docs]
@dataclass
class LHEInitRWGTWeight:
"""Information about a single weight inside or outside of a weight group."""
id: str
"""ID of the weight"""
name: str
"""Weight description text"""
extra_attributes: dict[str, str] = field(default_factory=dict)
"""Weight XML attributes not represented by dedicated fields"""
def __post_init__(self) -> None:
"""Remove schema typed owned information from attributes dict to avoid duplication and potential inconsistencies."""
self.extra_attributes.pop("id", None)
@property
def attributes(self) -> dict[str, str]:
"""Return all the attributes of the weight, including the ID."""
# class schema typed attributes take precedence over extra_attributes in case of overlap to avoid inconsistencies
return {**self.extra_attributes, "id": self.id}
[docs]
@dataclass
class LHEInitRWGTWeightGroup:
"""Information about a weight group."""
name: Optional[str] = (
None # Normally this is required, i.e. not Optional, but old Madgraph-2.0.0 uses 'type' instead of 'name'...
)
"""Name of the weight group"""
combine: Optional[str] = None
"""Combination method of the weight group"""
weights: list[LHEInitRWGTWeight] = field(default_factory=list)
"""List of weight information"""
extra_attributes: dict[str, str] = field(default_factory=dict)
"""Weight group XML attributes not represented by dedicated fields"""
@property
def attributes(self) -> dict[str, str]:
"""Return all the attributes of the weight group, including the name and combine attributes."""
attrs = {}
if self.name is not None:
attrs["name"] = self.name
if self.combine is not None:
attrs["combine"] = self.combine
# class schema typed attributes take precedence over extra_attributes in case of overlap to avoid inconsistencies
return {**self.extra_attributes, **attrs}
def __post_init__(self) -> None:
"""Remove schema typed owned information from attributes dict to avoid duplication and potential inconsistencies."""
name = self.extra_attributes.pop("name", None)
if self.name is None:
self.name = name
combine = self.extra_attributes.pop("combine", None)
if self.combine is None:
self.combine = combine
InitRWGTEntry = Union[LHEInitRWGTWeight, LHEInitRWGTWeightGroup]
@dataclass
class LHEInitRWGT:
"""
Represents the <initrwgt> block of an LHE file as a dataclass.
"""
entries: list[InitRWGTEntry] = field(default_factory=list)
def iter_weights(self) -> Iterator[LHEInitRWGTWeight]:
"""Iterate over all weights in the <initrwgt> block, including those inside weight groups."""
for entry in self.entries:
if isinstance(entry, LHEInitRWGTWeight):
yield entry
else:
yield from entry.weights
def weights_by_id(self) -> dict[str, LHEInitRWGTWeight]:
"""Return a dictionary mapping weight IDs to LHEInitRWGTWeight instances for all weights in the <initrwgt> block."""
return {w.id: w for w in self.iter_weights()}
def index_to_id(self) -> dict[int, str]:
"""Return a dictionary mapping weight indices to weight IDs for all weights in the <initrwgt> block."""
return {i: w.id for i, w in enumerate(self.iter_weights())}
def tolhe(self) -> str:
"""
Return the init block as a string in LHE format.
Returns:
str: The init block as a string in LHE format.
"""
# weightgroups to xml
root = ET.Element("initrwgt")
for e in self.entries:
if isinstance(e, LHEInitRWGTWeightGroup):
weightgroup_elem = ET.SubElement(
root, "weightgroup", attrib=e.attributes
)
for value in e.weights:
weight_elem = ET.SubElement(
weightgroup_elem, "weight", attrib=value.attributes
)
weight_elem.text = value.name
else:
weight_elem = ET.SubElement(root, "weight", attrib=e.attributes)
weight_elem.text = e.name
_indent(root)
return ET.tostring(root, encoding="unicode", method="xml")
[docs]
@dataclass
class LHEGenerator:
"""Information about a generator."""
name: str
"""Name of the generator"""
version: str
"""Version of the generator"""
description: str
"""Description of the generator"""
extra_attributes: dict[str, str] = field(default_factory=dict)
"""Generator XML attributes not represented by dedicated fields"""
@property
def attributes(self) -> dict[str, str]:
"""Return all the attributes of the generator element, including the name and version attributes."""
# class schema typed attributes take precedence over extra_attributes in case of overlap to avoid inconsistencies
return {**self.extra_attributes, "name": self.name, "version": self.version}
def __post_init__(self) -> None:
"""Remove schema typed owned information from attributes dict to avoid duplication and potential inconsistencies."""
self.extra_attributes.pop("name", None)
self.extra_attributes.pop("version", None)
[docs]
def tolhe(self) -> str:
"""
Return the generator information as a string in LHE format.
Returns:
str: The generator information as a string in LHE format.
"""
opening_tag = _open_xml_tag("generator", self.attributes)
return f"{opening_tag}{self.description}</generator>"
[docs]
@dataclass
class LHEInit:
"""Store the <init> block as a dataclass."""
initInfo: LHEInitInfo
"""Init information"""
procInfo: list[LHEProcInfo]
"""Process information"""
generators: list[LHEGenerator]
"""Generator information"""
[docs]
def tolhe(self) -> str:
"""
Return the init block as a string in LHE format.
Returns:
str: The init block as a string in LHE format.
"""
return (
"<init>\n"
+ self.initInfo.tolhe()
+ "\n"
+ "\n".join(
[p.tolhe() for p in self.procInfo]
+ [g.tolhe() for g in self.generators]
)
+ "\n"
+ "</init>"
)
@classmethod
def _fromcontext(cls, _root: ET.Element, context: Any) -> "LHEInit":
initInfo = None
procInfo = []
generators = []
for event, element in context:
if (
element.tag == "generator"
and "version" in element.attrib
and event == "end"
):
if "name" in element.attrib:
# lhe-v3 has name and version
generator = LHEGenerator(
name=element.attrib["name"],
version=element.attrib["version"],
description=""
if element.text is None
else element.text.strip(),
extra_attributes=element.attrib.copy(),
)
generators.append(generator)
else:
# lhe-v2 has version and name is in the text
generator = LHEGenerator(
version=element.attrib["version"],
name="",
description=element.text.strip() if element.text else "",
extra_attributes=element.attrib.copy(),
)
generators.append(generator)
if (
element.tag == "init" and event == "end"
): # text is None before end-tag if event == "start", if there are sub-elements (e.g. MadGraph stores a <generator> tag there)
if element.text is None:
err = "<init> block has no text."
raise ValueError(err)
data = element.text.split("\n")[1:-1]
initInfo = LHEInitInfo.fromstring(data[0])
procInfo = [LHEProcInfo.fromstring(d) for d in data[1:]]
break
if initInfo is None:
err = "No <init> block found in the LHE file."
raise ValueError(err)
return LHEInit(
initInfo=initInfo,
procInfo=procInfo,
generators=generators,
)
[docs]
@dataclass
class LHEEvent:
"""
Store a single event in the LHE format.
"""
eventinfo: LHEEventInfo
"""Event information"""
particles: list[LHEParticle]
"""List of particles in the event"""
weights: dict[str, float] = field(default_factory=dict)
"""Event weights"""
scales: dict[str, float] = field(default_factory=dict)
"""Event scales"""
attributes: dict[str, str] = field(default_factory=dict)
"""Event attributes not represented by dedicated fields"""
optional: list[str] = field(default_factory=list)
"""Optional '#' comments stored in the event"""
_graph: Optional[graphviz.Digraph] = field(default=None, repr=False, compare=False)
"""Stores the graph representation of the event generated after first access of the property `lheevent.graph`"""
def __post_init__(self) -> None:
"""Set up a bidirectional relationship between event and particles."""
for p in self.particles:
p.event = self
[docs]
def tolhe(self, rwgt: bool = True, weights: bool = False) -> str:
"""
Return the event as a string in LHE format.
Args:
rwgt (bool): Include the weights in the 'rwgt' format.
weights (bool): Include the weights in the 'weights' format.
Returns:
str: The event as a string in LHE format.
"""
if rwgt and weights:
err = "Cannot specify both rwgt and weights formats simultaneously."
raise ValueError(err)
sweights = ""
if rwgt and self.weights:
sweights = "<rwgt>\n"
for k, v in self.weights.items():
sweights += f" <wgt id='{k}'>{v:11.4e}</wgt>\n"
sweights += "</rwgt>\n"
if weights and self.weights:
sweights = "<weights>\n"
for v in self.weights.values():
sweights += f"{v:11.4e}\n"
sweights += "</weights>\n"
sscales = ""
if self.scales:
sscales = (
"<scales "
+ " ".join(f"{k}='{v}'" for k, v in self.scales.items())
+ "/>\n"
)
soptional = ""
if self.optional:
soptional = "\n".join(self.optional) + "\n"
return (
_open_xml_tag("event", self.attributes)
+ "\n"
+ self.eventinfo.tolhe()
+ "\n"
+ "\n".join([p.tolhe() for p in self.particles])
+ "\n"
+ soptional
+ sweights
+ sscales
+ "</event>"
)
@classmethod
def _fromcontext(
cls,
root: ET.Element,
context: Any,
lheheader: Optional[LHEHeader] = None,
with_attributes: bool = True,
) -> Iterator["LHEEvent"]:
index_map = (
lheheader.initrwgt.index_to_id() if with_attributes and lheheader else {}
)
for event, element in context:
if event == "end" and element.tag == "event":
if element.text is None:
err = "<event> block has no text."
raise ValueError(err)
data = element.text.strip().split("\n")
eventdata_str, particles_str = data[0], data[1:]
eventinfo = LHEEventInfo.fromstring(eventdata_str)
particles = [
LHEParticle.fromstring(p)
for p in particles_str
if not p.strip().startswith("#")
]
if with_attributes:
weights = {}
scales = {}
attrib = element.attrib.copy()
optional = [
p.strip() for p in particles_str if p.strip().startswith("#")
]
for sub in element:
if sub.tag == "weights":
if sub.text is None:
err = "<weights> block has no text."
raise ValueError(err)
if not index_map:
err = "<initrwgt> is required to parse <weights> block but not found in the header."
raise ValueError(err)
for i, w in enumerate(sub.text.split()):
if w and index_map[i] not in weights:
weights[index_map[i]] = float(w)
elif sub.tag == "rwgt":
for r in sub:
if r.tag == "wgt":
if r.text is None:
err = "<wgt> block has no text."
raise ValueError(err)
weights[r.attrib["id"]] = float(r.text.strip())
elif sub.tag == "scales":
for k, v in sub.attrib.items():
scales[k] = float(v)
yield LHEEvent(
eventinfo=eventinfo,
particles=particles,
weights=weights,
scales=scales,
attributes=attrib,
optional=optional,
)
else:
yield LHEEvent(eventinfo, particles)
# Clear memory
element.clear()
root.clear()
if element.tag == "LesHouchesEvents" and event == "end":
return
@property
def graph(self) -> graphviz.Digraph:
"""
Get the `graphviz.Digraph` object.
The user now has full control ...
E.g., see the source with my_LHEEvent_instance.graph.source.
When not in notebooks the graph can easily be visualized with the
`graphviz.Digraph.render` or `graphviz.Digraph.view` functions, e.g.:
my_LHEEvent_instance.graph.render(filename="test", format="pdf", view=True, cleanup=True)
"""
if self._graph is None:
self._build_graph()
return self._graph
def _build_graph(self) -> None:
"""
Navigate the particles in the event and produce a Digraph in the DOT language.
"""
self._graph = graphviz.Digraph()
for i, p in enumerate(self.particles):
iid = int(p.id)
sid = str(iid)
try:
name = _PDGID2LaTeXNameMap[sid]
texlbl = f"${name}$"
label = f'<<table border="0" cellspacing="0" cellborder="0"><tr><td>{latex_to_html_name(name)}</td></tr></table>>'
except MatchingIDNotFound:
texlbl = sid
label = f'<<table border="0" cellspacing="0" cellborder="0"><tr><td>{texlbl}</td></tr></table>>'
self._graph.node(str(i), label=label, texlbl=texlbl)
for i, p in enumerate(self.particles):
for mother_idx in self.mother_indices(p):
self._graph.edge(str(mother_idx), str(i))
[docs]
def mother_indices(self, particle: LHEParticle) -> list[int]:
"""
Return the positional indices of the particle's mothers in ``self.particles``.
The LHE ``mother1``/``mother2`` fields are 1-based; absent mothers (0) are dropped.
"""
idxs = [particle.mother1 - 1, particle.mother2 - 1]
out: list[int] = []
for idx in idxs:
if idx < 0:
continue
if idx >= len(self.particles):
err = f"Mother index {idx + 1} out of range for event with {len(self.particles)} particles."
raise IndexError(err)
out.append(idx)
return out
[docs]
def mothers(self, particle: LHEParticle) -> list[LHEParticle]:
"""
Return a list of the particle's mothers.
"""
return [self.particles[idx] for idx in self.mother_indices(particle)]
def _repr_mimebundle_(
self,
include: Optional[Iterable[str]] = None,
exclude: Optional[Iterable[str]] = None,
**kwargs: dict[str, Any],
) -> Any:
"""
IPython display helper.
"""
return self.graph._repr_mimebundle_(include=include, exclude=exclude, **kwargs)
@dataclass
class LesHouchesEvents:
"""
Represents an LHE file as a dataclass.
"""
init: LHEInit
"""Init block"""
events: Iterable[LHEEvent] = field(default_factory=list)
"""Event block"""
header: Optional[LHEHeader] = None
"""Header block"""
comment: Optional[str] = None
"""Comment block"""
version: Optional[str] = None
"""Version of the LHE file"""
extra_attributes: dict[str, str] = field(default_factory=dict)
"""Attributes of the root LesHouchesEvents element"""
def __post_init__(self) -> None:
"""Remove schema typed owned information from attributes dict to avoid duplication and potential inconsistencies."""
version = self.extra_attributes.pop("version", None)
if self.version is None:
self.version = version
@property
def attributes(self) -> dict[str, str]:
"""Return all the attributes of the root LesHouchesEvents element, including the version."""
attrs = {}
if self.version is not None:
attrs["version"] = self.version
# class schema typed attributes take precedence over extra_attributes in case of overlap to avoid inconsistencies
return {**self.extra_attributes, **attrs}
def write(
self, output_stream: TWriteable, rwgt: bool = True, weights: bool = False
) -> TWriteable:
"""
Write the LHE file to an output stream.
"""
output_stream.write(_open_xml_tag("LesHouchesEvents", self.attributes) + "\n")
if self.comment is not None:
output_stream.write(f"<!-- {self.comment} -->\n")
if self.header is not None:
output_stream.write(self.header.tolhe() + "\n")
output_stream.write(self.init.tolhe() + "\n")
for e in self.events:
output_stream.write(e.tolhe(rwgt=rwgt, weights=weights) + "\n")
output_stream.write("</LesHouchesEvents>")
return output_stream
def tolhe(self, rwgt: bool = True, weights: bool = False) -> str:
"""
Return the LHE file as a string.
"""
return self.write(io.StringIO(), rwgt=rwgt, weights=weights).getvalue()
def tofile(
self,
filepath: str,
gz: bool = False,
rwgt: bool = True,
weights: bool = False,
) -> None:
"""
Write the LHE file.
Args:
filepath: Path to the output file.
gz: Whether to gzip the output file (ignored if filepath suffix is .gz/.gzip).
rwgt: Whether to include weights in 'rwgt' format.
weights: Whether to include weights in 'weights' format.
"""
# if filepath suffix is gz, write as gz
with _open_write_file(filepath, gz=gz) as f:
self.write(f, rwgt=rwgt, weights=weights)
@classmethod
def fromstring(
cls, string: str, with_attributes: bool = True, generator: bool = True
) -> "LHEFile":
"""
Create an LHEFile instance from a string in LHE format.
"""
return cls.frombuffer(
io.StringIO(string), with_attributes=with_attributes, generator=generator
)
@classmethod
def fromfile(
cls, filepath: PathLike, with_attributes: bool = True, generator: bool = True
) -> "LHEFile":
"""
Read an LHE file and return an LHEFile object.
"""
return cls.frombuffer(
_extract_fileobj(filepath),
with_attributes=with_attributes,
generator=generator,
)
@classmethod
def frombuffer(
cls,
fileobject: Union[
io.BufferedReader, gzip.GzipFile, io.StringIO, TextIO, BinaryIO
],
with_attributes: bool = True,
generator: bool = True,
) -> "LHEFile":
"""
Read an LHE file and return an LHEFile object.
"""
def _generator(lhef: LHEFile) -> Iterator[LHEEvent]:
try:
with fileobject as fileobj:
context = ET.iterparse(fileobj, events=["start", "end", "comment"])
_, root = next(context) # Get the root element
if root.tag != "LesHouchesEvents":
err = "Root element is not <LesHouchesEvents>."
raise ValueError(err)
else:
lhef.extra_attributes = root.attrib.copy()
# Re-run post-init now that extra_attributes is populated;
# construction used an empty dict so version was not set yet.
lhef.__post_init__()
# We do not allow other xml tags before <header> or <init>
event, element = next(context) # Get the first element in the file
# look for optional header first
if event == "comment":
# Here we extract e.g. the POWHEG run card stored in first <!-- ... --> comment block before the header
lhef.comment = element.text.strip() if element.text else None
event, element = next(
context
) # Get the next element in the file after the comment
if element.tag == "header" and event == "start":
lhef.header = LHEHeader._fromcontext(root, context)
event, element = next(
context
) # Get the second element in the file
else:
lhef.header = None
if element.tag == "init" and event == "start":
lheinit = LHEInit._fromcontext(root, context)
lhef.init = lheinit
else:
err = "No <init> block found in the LHE file."
raise ValueError(err)
# First yield allows caller to advance generator to read lheinit before consuming real events
yield LHEEvent(
eventinfo=LHEEventInfo(
nparticles=0,
pid=0,
weight=0.0,
scale=0.0,
aqed=0.0,
aqcd=0.0,
),
particles=[],
)
yield from LHEEvent._fromcontext(
root, context, lhef.header, with_attributes
)
except ET.ParseError as excep:
warnings.warn(f"Parse Error: {excep}", RuntimeWarning, stacklevel=1)
return
lhef = cls(
version=None, # dummy version, will be replaced
# dummy init, will be replaced
init=LHEInit(
initInfo=LHEInitInfo(0, 0, 0.0, 0.0, 0, 0, 0, 0, 0, 0),
procInfo=[],
generators=[],
),
header=None,
events=[],
comment=None,
)
events = _generator(lhef)
try:
next(events) # advance to read lheinit and version
except StopIteration:
# If generator stops without yielding, it means no init was read
err = "No or faulty <header>/<init> block found in the LHE file."
raise ValueError(err) from None
lhef.events = events if generator else list(events)
return lhef
@staticmethod
def count_events(filepath: PathLike) -> int:
"""
Efficiently count the number of events in an LHE file without loading them into memory.
Args:
filepath: Path to the LHE file.
Returns:
Number of events in the file, or -1 if parsing fails.
"""
try:
with _extract_fileobj(filepath) as fileobj:
context = ET.iterparse(fileobj, events=["start", "end"])
_, root = next(context) # Get the root element
count = 0
for event, element in context:
if event == "end" and element.tag == "event":
count += 1
# Clear the element to free memory
element.clear()
# Root tracks sub-elements -> clear all sub-elements
root.clear()
if event == "end" and element.tag == "LesHouchesEvents":
return count
except ET.ParseError as excep:
warnings.warn(f"Parse Error: {excep}", RuntimeWarning, stacklevel=1)
return -1
# Backwards compatibility
LHEFile = LesHouchesEvents
def _extract_fileobj(filepath: PathLike) -> Union[io.BufferedReader, gzip.GzipFile]:
"""
Checks to see if a file is compressed, and if so, extract it with gzip
so that the uncompressed file can be returned.
It returns a file object containing XML data that will be ingested by
``xml.etree.ElementTree.iterparse``.
Args:
filepath: A path-like object or str.
Returns:
_io.BufferedReader or gzip.GzipFile: A file object containing XML data.
"""
with open(filepath, "rb") as gzip_file:
header = gzip_file.read(2)
gzip_magic_number = b"\x1f\x8b"
return (
gzip.GzipFile(filepath) if header == gzip_magic_number else open(filepath, "rb")
)
def _open_write_file(filepath: str, gz: bool = False) -> TextIO:
if filepath.endswith((".gz", ".gzip")) or gz:
return gzip.open(filepath, "wt")
return open(filepath, "w")
# we import this later to avoid circular imports
from .awkward import to_awkward # noqa: E402