Out-of-the-box plotting script

A ready-to-use python script for plotting simulation results is available at plot_parallel.py. Feel free to use it out-of-the-box or to modify it to suit your needs.


Most of its dependencies are standard Python packages, that come with a default Anaconda installation or can be installed with pip or conda: os, matplotlib, sys, argparse, matplotlib, scipy.

Additional dependencies are yt >= 4.0.1 and mpi4py.

Run serial

Executing the script with

python plot_parallel.py

will loop through plotfiles named plt????? (e.g., plt00000, plt00100 etc.) and save one image per plotfile. For a 2D simulation, a 2D colormap of the Ez field is plotted by default, with 1/20 of particles of each species (with different colors). For a 3D simulation, a 2D colormap of the central slices in y is plotted, and particles are handled the same way.

The script reads command-line options (which field and particle species, rendering with yt or matplotlib, etc.). For the full list of options, run

python plot_parallel.py --help

In particular, option --plot_Ey_max_evolution shows you how to plot the evolution of a scalar quantity over time (by default, the max of the Ey field). Feel free to modify it to plot the evolution of other quantities.

Run parallel

To execute the script in parallel, you can run for instance

mpirun -np 4 python plot_parallel.py --parallel

In this case, MPI ranks will share the plotfiles to process as evenly as possible. Note that each plotfile is still processed in serial. When option --plot_Ey_max_evolution is on, the scalar quantity is gathered to rank 0, and rank 0 plots the image.

If all dependencies are satisfied, the script can be used on Summit or Cori. For instance, the following batch script illustrates how to submit a post-processing batch job on Cori haswell with some options:


# Copyright 2019 Maxence Thevenet
# This file is part of WarpX.
# License: BSD-3-Clause-LBNL

#SBATCH --job-name=postproc
#SBATCH --time=00:20:00
#SBATCH -C haswell
#SBATCH -q regular
#SBATCH -e postproce.txt
#SBATCH -o postproco.txt
#SBATCH --mail-type=end
#SBATCH --account=m2852


# Requires python3 and yt > 3.5
srun -n 32 -c 16 python plot_parallel.py --path <path/to/plotfiles> --plotlib=yt --parallel