"""
Python interface to read Les Houches Event (LHE) files.
"""
import gzip
import io
import xml.etree.ElementTree as ET
from collections.abc import Iterable
from typing import Optional
import graphviz
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__
from pylhe.awkward import to_awkward
__all__ = [
"LHEEvent",
"LHEEventInfo",
"LHEFile",
"LHEInit",
"LHEInitInfo",
"LHEParticle",
"LHEProcInfo",
"__version__",
"read_lhe",
"read_lhe_file",
"read_lhe_init",
"read_lhe_with_attributes",
"read_num_events",
"to_awkward",
"write_lhe_file",
"write_lhe_file_path",
"write_lhe_file_string",
"write_lhe_string",
]
def __dir__():
return __all__
# retrieve mapping of PDG ID to particle name as LaTeX string
_PDGID2LaTeXNameMap, _ = DirectionalMaps("PDGID", "LATEXNAME", converters=(int, str))
[docs]
class LHEEvent:
"""
Store a single event in the LHE format.
"""
[docs]
def __init__(
self, eventinfo, particles, weights=None, attributes=None, optional=None
):
self.eventinfo = eventinfo
self.particles = particles
self.weights = weights
self.attributes = attributes
self.optional = optional
for p in self.particles:
p.event = self
self._graph = None
[docs]
def tolhe(self, rwgt=True, weights=False):
"""
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.
"""
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"
return (
"<event>\n"
+ self.eventinfo.tolhe()
+ "\n"
+ "\n".join([p.tolhe() for p in self.particles])
+ "\n"
+ sweights
+ "</event>"
)
@property
def graph(self):
"""
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):
"""
Navigate the particles in the event and produce a Digraph in the DOT language.
"""
def safe_html_name(name):
"""
Get a safe HTML name from the LaTex name.
"""
try:
return latex_to_html_name(name)
except Exception:
return name
self._graph = graphviz.Digraph()
for i, p in enumerate(self.particles):
try:
iid = int(p.id)
name = _PDGID2LaTeXNameMap[iid]
texlbl = f"${name}$"
label = f'<<table border="0" cellspacing="0" cellborder="0"><tr><td>{safe_html_name(name)}</td></tr></table>>'
except MatchingIDNotFound:
texlbl = str(int(p.id))
label = f'<<table border="0" cellspacing="0" cellborder="0"><tr><td>{texlbl}</td></tr></table>>'
self._graph.node(
str(i), label=label, attr_dict=str(p.__dict__), texlbl=texlbl
)
for i, p in enumerate(self.particles):
for mom in p.mothers():
self._graph.edge(str(self.particles.index(mom)), str(i))
def _repr_mimebundle_(
self,
include=None,
exclude=None,
**kwargs,
):
"""
IPython display helper.
"""
try:
return self.graph._repr_mimebundle_(
include=include, exclude=exclude, **kwargs
)
except AttributeError:
return {"image/svg+xml": self.graph._repr_svg_()} # for graphviz < 0.19
[docs]
class LHEEventInfo:
"""
Store the event information in the LHE format.
"""
fieldnames = ["nparticles", "pid", "weight", "scale", "aqed", "aqcd"]
[docs]
def __init__(self, **kwargs):
if set(kwargs.keys()) != set(self.fieldnames):
msg = f"LHEEventInfo constructor expects fields {self.fieldnames}! Got {kwargs.keys()}."
raise RuntimeError(msg)
for k, v in kwargs.items():
setattr(self, k, v)
[docs]
def tolhe(self):
"""
Return the event info as a string in LHE format.
Returns:
str: The event info as a string in LHE format.
"""
return "{:3d} {:6d} {: 15.10e} {: 15.10e} {: 15.10e} {: 15.10e}".format(
*[int(getattr(self, f)) for f in self.fieldnames[:2]],
*[getattr(self, f) for f in self.fieldnames[2:]],
)
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEEventInfo":
"""
Create an `LHEEventInfo` instance from a string in LHE format.
"""
return cls(**dict(zip(cls.fieldnames, map(float, string.split()))))
[docs]
class LHEParticle:
"""
Represents a single particle in the LHE format.
"""
fieldnames = [
"id",
"status",
"mother1",
"mother2",
"color1",
"color2",
"px",
"py",
"pz",
"e",
"m",
"lifetime",
"spin",
]
[docs]
def __init__(self, **kwargs):
if set(kwargs.keys()) != set(self.fieldnames):
msg = f"LHEParticle constructor expects fields {self.fieldnames}! Got {kwargs.keys()}."
raise RuntimeError(msg)
for k, v in kwargs.items():
setattr(self, k, v)
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEParticle":
"""
Create an `LHEParticle` instance from a string in LHE format.
"""
return cls(**dict(zip(cls.fieldnames, map(float, string.split()))))
[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 "{:5d} {:3d} {:3d} {:3d} {:3d} {:3d} {: 15.8e} {: 15.8e} {: 15.8e} {: 15.8e} {: 15.8e} {: 10.4e} {: 10.4e}".format(
*[int(getattr(self, f)) for f in self.fieldnames[:6]],
*[getattr(self, f) for f in self.fieldnames[6:]],
)
[docs]
def mothers(self) -> list["LHEParticle"]:
"""
Return a list of the particle's mothers.
"""
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, level=0):
"""
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]
class LHEInitInfo(dict):
"""Store the first line of the <init> block as dict."""
fieldnames = [
"beamA",
"beamB",
"energyA",
"energyB",
"PDFgroupA",
"PDFgroupB",
"PDFsetA",
"PDFsetB",
"weightingStrategy",
"numProcesses",
]
[docs]
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
[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 (
" {: 6d} {: 6d} {: 14.7e} {: 14.7e} {: 5d} {: 5d} {: 5d} {: 5d} {: 5d} {: 5d}"
).format(
int(self["beamA"]),
int(self["beamB"]),
self["energyA"],
self["energyB"],
int(self["PDFgroupA"]),
int(self["PDFgroupB"]),
int(self["PDFsetA"]),
int(self["PDFsetB"]),
int(self["weightingStrategy"]),
int(self["numProcesses"]),
)
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEInitInfo":
"""
Create an `LHEInitInfo` instance from a string in LHE format.
"""
return cls(**dict(zip(cls.fieldnames, map(float, string.split()))))
[docs]
class LHEProcInfo(dict):
"""Store the process info block as dict."""
fieldnames = ["xSection", "error", "unitWeight", "procId"]
[docs]
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
[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 ("{: 14.7e} {: 14.7e} {: 14.7e} {: 5d}").format(
self["xSection"], self["error"], self["unitWeight"], int(self["procId"])
)
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEProcInfo":
"""
Create an `LHEProcInfo` instance from a string in LHE format.
"""
return cls(**dict(zip(cls.fieldnames, map(float, string.split()))))
[docs]
class LHEInit(dict):
"""Store the <init> block as dict."""
fieldnames = ["initInfo", "procInfo", "weightgroup", "LHEVersion"]
[docs]
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
[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.
"""
# weightgroups to xml
root = ET.Element("initrwgt")
for _k, v in self["weightgroup"].items():
weightgroup_elem = ET.SubElement(root, "weightgroup", **v["attrib"])
for _key, value in v["weights"].items():
weight_elem = ET.SubElement(
weightgroup_elem, "weight", **value["attrib"]
)
weight_elem.text = value["name"]
_indent(root)
sweightgroups = ET.tostring(root, encoding="unicode", method="xml")
return (
"<init>\n"
+ self["initInfo"].tolhe()
+ "\n"
+ "\n".join([p.tolhe() for p in self["procInfo"]])
+ "\n"
+ f"{sweightgroups}"
+ "</init>"
)
def __getitem__(self, key):
"""
custom backwards compatibility get for dict
"""
if key not in self:
return self["initInfo"][key]
return super().__getitem__(key)
def __setitem__(self, key, value):
"""
custom backwards compatibility set for dict
"""
if key not in self:
self["initInfo"][key] = value
else:
self.super().__setitem__(key, value)
[docs]
@classmethod
def frombuffer(cls, fileobj):
"""Create an instance from a file-like object (buffer)."""
initDict = {}
for _event, element in ET.iterparse(fileobj, events=["start", "end"]):
if element.tag == "init":
data = element.text.split("\n")[1:-1]
initDict["initInfo"] = LHEInitInfo.fromstring(data[0])
initDict["procInfo"] = [LHEProcInfo.fromstring(d) for d in data[1:]]
if element.tag == "initrwgt":
initDict["weightgroup"] = {}
index = 0
for child in element:
# Find all weightgroups
if child.tag == "weightgroup" and child.attrib != {}:
if "type" in child.attrib:
wg_type = child.attrib["type"]
elif "name" in child.attrib:
wg_type = child.attrib["name"]
else:
ae = "weightgroup must have attribute 'type' or 'name'."
raise AttributeError(ae)
_temp = {"attrib": child.attrib, "weights": {}}
# Iterate over all weights in this weightgroup
for w in child:
if w.tag != "weight":
continue
if "id" not in w.attrib:
ae = "weight must have attribute 'id'"
raise AttributeError(ae)
wg_id = w.attrib["id"]
_temp["weights"][wg_id] = {
"attrib": w.attrib,
"name": w.text.strip() if w.text else "",
"index": index,
}
index += 1
initDict["weightgroup"][wg_type] = _temp
if element.tag == "LesHouchesEvents":
initDict["LHEVersion"] = float(element.attrib["version"])
if element.tag == "event":
break
return cls(**initDict)
[docs]
@classmethod
def fromstring(cls, string: str) -> "LHEInit":
"""
Create an `LHEEventInfo` instance from a string in LHE format.
"""
return cls.frombuffer(io.StringIO(string))
[docs]
class LHEFile:
"""
Represents an LHE file.
"""
[docs]
def __init__(
self, init: LHEInit = None, events: Optional[Iterable[LHEEvent]] = None
):
self.init = init
self.events = events
[docs]
def write(self, output_stream, rwgt=True, weights=False):
"""
Write the LHE file to an output stream.
"""
output_stream.write(f'<LesHouchesEvents version="{self.init["LHEVersion"]}">\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
[docs]
def tolhe(self, rwgt=True, weights=False) -> str:
"""
Return the LHE file as a string.
"""
return self.write(io.StringIO(), rwgt=rwgt, weights=weights).getvalue()
[docs]
def read_lhe_file(filepath, with_attributes=True) -> LHEFile:
"""
Read an LHE file and return an LHEFile object.
"""
lheinit = read_lhe_init(filepath)
lheevents = (
read_lhe_with_attributes(filepath) if with_attributes else read_lhe(filepath)
)
return LHEFile(init=lheinit, events=lheevents)
def _extract_fileobj(filepath):
"""
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")
)
[docs]
def read_lhe_init(filepath) -> LHEInit:
"""
Read and return the init blocks. This encodes the weight group
and related things according to https://arxiv.org/abs/1405.1067
Args:
filepath: A path-like object or str.
Returns:
dict: Dictionary containing the init blocks of the LHE file.
"""
with _extract_fileobj(filepath) as fileobj:
return LHEInit.frombuffer(fileobj)
[docs]
def read_lhe(filepath):
"""
Read and yield the events in the LHE file.
"""
try:
with _extract_fileobj(filepath) as fileobj:
context = ET.iterparse(fileobj, events=["start", "end"])
_, root = next(context) # Get the root element
for event, element in context:
if event == "end" and element.tag == "event":
data = element.text.strip().split("\n")
eventdata, particles = data[0], data[1:]
eventinfo = LHEEventInfo.fromstring(eventdata)
particles = particles[: int(eventinfo.nparticles)]
particle_objs = [LHEParticle.fromstring(p) for p in particles]
yield LHEEvent(eventinfo, particle_objs)
# Clear the element to free memory
element.clear()
# Root tracks sub-elements -> clear all sub-elements
root.clear()
except ET.ParseError as excep:
print("WARNING. Parse Error:", excep)
return
def _get_index_to_id_map(init):
"""
Produce a dictionary to map weight indices to the id of the weight.
It is used for LHE files where there is only a list of weights per event.
This dictionary is then used to map the list of weights to their weight id.
Ideally, this needs to be done only once and the dictionary can be reused.
Args:
init (dict): init block as returned by read_lhe_init
Returns:
dict: {weight index: weight id}
"""
ret = {}
for wg in init["weightgroup"].values():
for id, w in wg["weights"].items():
ret[w["index"]] = id
return ret
[docs]
def read_lhe_with_attributes(filepath):
"""
Iterate through file, similar to read_lhe but also set
weights and attributes.
"""
index_map = None
try:
with _extract_fileobj(filepath) as fileobj:
context = ET.iterparse(fileobj, events=["start", "end"])
_, root = next(context) # Get the root element
for event, element in context:
if event == "end" and element.tag == "event":
eventdict = {}
data = element.text.strip().split("\n")
eventdata, particles = data[0], data[1:]
eventdict["eventinfo"] = LHEEventInfo.fromstring(eventdata)
eventdict["particles"] = []
eventdict["weights"] = {}
eventdict["attrib"] = element.attrib
eventdict["optional"] = []
for p in particles:
if not p.strip().startswith("#"):
eventdict["particles"] += [LHEParticle.fromstring(p)]
else:
eventdict["optional"].append(p.strip())
for sub in element:
if sub.tag == "weights":
if not index_map:
index_map = _get_index_to_id_map(
read_lhe_init(filepath)
)
for i, w in enumerate(sub.text.split()):
if w and index_map[i] not in eventdict["weights"]:
eventdict["weights"][index_map[i]] = float(w)
if sub.tag == "rwgt":
for r in sub:
if r.tag == "wgt":
eventdict["weights"][r.attrib["id"]] = float(
r.text.strip()
)
# yield eventdict
yield LHEEvent(
eventdict["eventinfo"],
eventdict["particles"],
eventdict["weights"],
eventdict["attrib"],
eventdict["optional"],
)
# Clear processed elements
element.clear()
# Root tracks sub-elements -> clear all sub-elements
root.clear()
except ET.ParseError as excep:
print("WARNING. Parse Error:", excep)
return
[docs]
def read_num_events(filepath) -> int:
"""
Moderately efficient way to get the number of events stored in a file.
"""
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()
return count
except ET.ParseError as excep:
print("WARNING. Parse Error:", excep)
return -1
[docs]
def write_lhe_file_string(
lhefile: LHEFile, rwgt: bool = True, weights: bool = False
) -> str:
"""
Return the LHE file as a string.
"""
return lhefile.tolhe(rwgt=rwgt, weights=weights)
[docs]
def write_lhe_string(lheinit, lheevents, rwgt=True, weights=False):
"""
Return the LHE file as a string.
.. deprecated:: 0.9.1
Instead of :func:`~pylhe.write_lhe_string` use :func:`~pylhe.write_lhe_file_string`
.. warning:: :func:`~pylhe.write_lhe_string` will be removed in
``pylhe`` ``v0.11.0``.
"""
return write_lhe_file_string(
LHEFile(init=lheinit, events=lheevents), rwgt=rwgt, weights=weights
)
def _open_write_file(filepath: str, gz: bool = False):
if filepath.endswith((".gz", ".gzip")) or gz:
return gzip.open(filepath, "wt")
return open(filepath, "w")
[docs]
def write_lhe_file_path(
lhefile: LHEFile,
filepath: str,
gz: bool = False,
rwgt: bool = True,
weights: bool = False,
):
"""
Write the LHE file.
"""
# if filepath suffix is gz, write as gz
with _open_write_file(filepath, gz=gz) as f:
lhefile.write(f, rwgt=rwgt, weights=weights)
[docs]
def write_lhe_file(lheinit, lheevents, filepath, gz=False, rwgt=True, weights=False):
"""
Write the LHE file.
.. deprecated:: 0.9.1
Instead of :func:`~pylhe.write_lhe_file` use :func:`~pylhe.write_lhe_file_path`
.. warning:: :func:`~pylhe.write_lhe_file` will be removed in
``pylhe`` ``v0.11.0``.
"""
write_lhe_file_path(
LHEFile(init=lheinit, events=lheevents),
filepath,
gz=gz,
rwgt=rwgt,
weights=weights,
)