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import sys
from pathlib import Path
import awkward as ak
import numpy as np
import cupy as cp
sys.path.insert(0, str(Path(__file__).parent))
from helpers import filter_lists, list_sizes, select_lists, transform_lists # noqa: E402
# 3 events with different numbers of electrons and muons in each
# (numerical values are made up and aren't physically meaningful)
# ---
# legend:
# - 'pt': transverse momentum
# - 'eta': pseudorapidity (collider detector angle, e.g. CMS detector)
# - 'phi': azimuthal angle (collider detector angle, e.g. CMS detector)
electrons = ak.Array(
[
# 2 electrons
{"pt": [50.0, 60.0], "eta": [2.1, 2.2], "phi": [0.6, 0.7]},
# 1 electron
{"pt": [30.0], "eta": [-1.5], "phi": [0.3]},
# 0 electrons
{"pt": [], "eta": [], "phi": []},
]
)
muons = ak.Array(
[
# 1 muon
{"pt": [45.0], "eta": [2.5], "phi": [0.4]},
# 2 muons
{"pt": [25.0, 35.0], "eta": [-2.0, 1.0], "phi": [0.5, 0.6]},
# 1 muon
{"pt": [15.0], "eta": [0.0], "phi": [0.7]},
]
)
events = ak.zip({"electrons": electrons, "muons": muons}, depth_limit=1)
def invariant_mass(two_particles: ak.Array) -> ak.Array:
"""Compute invariant mass of two particles given their pt, eta, phi."""
pt1, eta1, phi1 = (
two_particles[:, 0].pt,
two_particles[:, 0].eta,
two_particles[:, 0].phi,
)
pt2, eta2, phi2 = (
two_particles[:, 1].pt,
two_particles[:, 1].eta,
two_particles[:, 1].phi,
)
# https://en.wikipedia.org/wiki/Invariant_mass#Collider_experiments
m2 = 2 * pt1 * pt2 * (np.cosh(eta1 - eta2) - np.cos(phi1 - phi2))
return np.sqrt(m2)
def physics_analysis(events: ak.Array) -> ak.Array:
"""
A oversimplified physics analysis selecting events with exactly 2 leptons (electrons or muons)
and computing their invariant mass.
"""
# select only electrons with pt > 40
selected_electrons = events.electrons[events.electrons.pt > 40.0]
# select only muons with pt > 20 and abs(eta) < 2.4
selected_muons = events.muons[
(events.muons.pt > 20.0) & (abs(events.muons.eta) < 2.4)
]
# choose exactly 2 leptons (electrons or muons)
two_electrons = selected_electrons[ak.num(
selected_electrons.pt, axis=-1) == 2]
two_muons = selected_muons[ak.num(selected_muons.pt, axis=-1) == 2]
return {
"electron": invariant_mass(two_electrons),
"muon": invariant_mass(two_muons),
}
def physics_analysis_gpu(events: ak.Array) -> ak.Array:
"""
A oversimplified physics analysis selecting events with exactly 2 leptons (electrons or muons)
and computing their invariant mass.
"""
# select only electrons with pt > 40
selected_electrons = events.electrons[events.electrons.pt > 40.0]
# select only muons with pt > 20 and abs(eta) < 2.4
selected_muons = events.muons[
(events.muons.pt > 20.0) & (abs(events.muons.eta) < 2.4)
]
# choose exactly 2 leptons (electrons or muons)
two_electrons = selected_electrons[ak.num(
selected_electrons.pt, axis=-1) == 2]
two_muons = selected_muons[ak.num(
selected_muons.pt, axis=-1) == 2]
return {
"electron": invariant_mass(two_electrons),
"muon": invariant_mass(two_muons),
}
def physics_analysis_cccl(events: ak.Array) -> ak.Array:
"""
CCCL-based physics analysis selecting events with exactly 2 leptons (electrons or muons)
and computing their invariant mass using cuda.compute primitives.
"""
def cond_muon(x):
return (x[0] > 20.0) & (abs(x[1]) < 2.4)
def cond_electron(x):
return x[0] > 40.0
selected_muons = filter_lists(events.muons, cond_muon)
selected_electrons = filter_lists(events.electrons, cond_electron)
two_muons = select_lists(
selected_muons, (list_sizes(selected_muons) == 2).astype('int8'))
two_electrons = select_lists(
selected_electrons, (list_sizes(selected_electrons) == 2).astype('int8'))
def invariant_mass(two_particles):
"""Compute invariant mass of two particles given their pt, eta, phi."""
pt1, eta1, phi1 = (
two_particles[0][0],
two_particles[0][1],
two_particles[0][2],
)
pt2, eta2, phi2 = (
two_particles[1][0],
two_particles[1][1],
two_particles[1][2],
)
# https://en.wikipedia.org/wiki/Invariant_mass#Collider_experiments
m2 = 2 * pt1 * pt2 * (np.cosh(eta1 - eta2) - np.cos(phi1 - phi2))
return m2 ** 0.5
masses_electrons = cp.zeros(len(two_electrons), dtype=np.float64)
masses_muons = cp.zeros(len(two_muons), dtype=np.float64)
transform_lists(two_muons, masses_muons, 2, invariant_mass)
transform_lists(two_electrons, masses_electrons, 2, invariant_mass)
return {
"electron": masses_electrons,
"muon": masses_muons,
}
if __name__ == "__main__":
# ipython -i studies/cccl/playground.py to play around with `events` and `physics_analysis`
# Run original function
inv_mass = physics_analysis(events)
print("Original physics_analysis() results:")
print(" Electron invariant masses (in GeV):", inv_mass["electron"])
print(" Muon invariant masses (in GeV):", inv_mass["muon"])
events_gpu = ak.to_backend(events, "cuda")
# Run Awkward Array on GPU function
inv_mass_gpu = physics_analysis_gpu(events_gpu)
print("\nGPU physics_analysis_gpu() results:")
print(" Electron invariant masses (in GeV):", inv_mass_gpu["electron"])
print(" Muon invariant masses (in GeV):", inv_mass_gpu["muon"])
# Run CCCL-based function
inv_mass_cccl = physics_analysis_cccl(events_gpu)
print("\nCCCL physics_analysis_cccl() results:")
print(" Electron invariant masses (in GeV):", inv_mass_cccl["electron"])
print(" Muon invariant masses (in GeV):", inv_mass_cccl["muon"])
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