Getting Started

Getting Started#

FLARE can be accessed from two sources, from the key4HEP nightly stack or from PyPI.

Access from key4HEP#

The key4HEP is an open source turnkey software package that provides access to high quality proven HEP software solutions for all. It includes a huge number of commandline tools for generating Monte Carlo simulation data for any experiment configuration. It also includes its own analysis tooling by way of the FCCAnalyses.

The key4HEP is provided via the CernVM File System, also known as the CVMFS. To gain access to FLARE one must source the nightly version of key4HEP:

$ source < INSERT PATH TO NIGHTLY STACK>

Install from PyPI#

To install from PyPI, follow this basic install process. It is recommended you use a virtual environment. To begin, a working version of python>3.8 must be installed on your system. If one is not natively available, setup the key4HEP software from the CVMFS.

$ source /cvmfs/fcc.cern.ch/sw/latest/setup.sh

Next, create a virtual environment. This can be done in many ways however, the simplest is to use the venv package provided by python.

$ python3 -m venv .venv

Activate your virtual environment. If venv was used, run the following command:

$ source .venv/bin/activate

Lastly, you can install hep-flare to your virtual environment. An example is shown below using pip.

(.venv)$ pip3 install hep-flare

Running Your First FLARE Workflow#

Here we will clone the FLARE Examples repository to access the many examples available within.

(.venv)$ git clone https://github.com/CamCoop1/FLARE-examples
(.venv)$ cd FCCAnalysis_workflow/higgs_mass_example

In this example, the FCCAnalyses tool is going to be utilized to orchestrate and run an analysis workflow investigating the Higgs mass at the FCCee.

Note

Inside the flare.yaml, the batch_system=slurm. If your machine does not support slurm you can change this to one of the following:

  • htcondor

  • lsf

  • local

Where local will mean FLARE does not submit to any batch system. Instead it will run the entire workflow on your local working node.

To run this workflow, invoke the FLARE Commandline Tool as shown below.

(.venv)$ flare run analysis

How The FCCAnalyses Workflow Is Staged#

This workflow is staged by having three FCCAnalyses steering scripts, each prefixed to indicate the order in which FLARE will run these tasks. That is:

  • stage1_flavor.py

  • stage2_histmaker_flavor.py

  • plots_flavor.py

At a maximum FLARE can orchestrate and run:

  1. stage1

  2. stage2

  3. stage3

  4. final

  5. plots

The hierarchy is always upheld but a user need not use all the available prefixes. For example, one could stage their FLARE workflow with the following files:

$ ls
stage2_test.py stage3_test.py plots_test.py

FLARE will reference its hierarchy and schedule the Tasks such that stage2 -> stage3 -> plots.