Compare standard vs FFTW scattering calculations for hard spheres

Test ScatteringFFTW against Scattering for a simple hard-sphere system.

import sys
import subprocess
import argparse
import random
import unittest

# define parameters of a pure component NVT MC hard sphere simulation
params = {
    "cubic_side_length": 8, "fstprt": "/feasst/particle/atom.fstprt",
    "num_particles": 128,
    "trials_per": 1e6, "hours_per_checkpoint": 1, "seed": random.randrange(int(1e9)), "num_hours": 5*24,
    "equilibration": 1e5, "production": 1e6, "num_nodes": 1, "procs_per_node": 1, "script": __file__}
params["num_minutes"] = round(params["num_hours"]*60)
params["num_hours_terminate"] = 0.95*params["num_hours"]*params["procs_per_node"]

# write fst script to run a single simulation
def mc_hs(params=params, script_file="launch.txt"):
    with open(script_file, "w") as myfile: myfile.write("""
RandomMT19937 seed {seed}
Configuration cubic_side_length {cubic_side_length} particle_type0 {fstprt}
Potential Model HardSphere VisitModel VisitModelCell min_length 1
ThermoParams beta 1 chemical_potential 1
TrialTranslate weight 1 tunable_param 0.2 tunable_target_acceptance 0.25
Log trials_per_write {trials_per} output_file hs.csv
CheckEnergy trials_per_update {trials_per} tolerance 1e-8
Checkpoint checkpoint_file hs.fst num_hours_terminate {num_hours_terminate}

# gcmc initialization and nvt equilibration
TrialAdd particle_type 0
Run until_num_particles {num_particles}
RemoveTrial name TrialAdd
Run num_trials {equilibration}

# nvt production
Movie trials_per_write {trials_per} output_file
PairDistribution trials_per_update 1000 trials_per_write {trials_per} dr 0.025 output_file hs_gr.csv
Scattering trials_per_update 100 trials_per_write {trials_per} num_frequency 10 output_file hs_iq.csv
ScatteringFFTW trials_per_update 100 trials_per_write {trials_per} bin_spacing 0.1 delta_rho 1 output_file hs_iq_fftw.csv
Run num_trials {production}

# write slurm script
def slurm_queue():
    with open("slurm.txt", "w") as myfile: myfile.write("""#!/bin/bash
#SBATCH -n {procs_per_node} -N {num_nodes} -t {num_minutes}:00 -o hostname_%j.out -e hostname_%j.out
echo "Running {script} ID $SLURM_JOB_ID on $(hostname) at $(date) in $PWD"
cd $PWD
export OMP_NUM_THREADS={procs_per_node}
python {script} --run_type 0 --task $SLURM_ARRAY_TASK_ID
if [ $? == 0 ]; then
  echo "Job is done"
  echo "Job is terminating, to be restarted again"
echo "Time is $(date)"

# parse arguments
parser = argparse.ArgumentParser()
parser.add_argument('--run_type', '-r', type=int, default=0, help="0: run, 1: submit to queue")
parser.add_argument('--task', type=int, default=0, help="input by slurm scheduler. If >0, restart from checkpoint.")
args = parser.parse_args()

# after the simulation is complete, perform some analysis
class TestFlatHistogramHS(unittest.TestCase):
    def test(self):
        import numpy as np
        import math
        import pandas as pd
        from pyfeasst import scattering
        iq=pd.read_csv('hs_iq.csv', comment="#")
        grp = iq.groupby('q', as_index=False)
        self.assertAlmostEqual(iq['i'][3810], 5.72894, delta=0.4)
        self.assertAlmostEqual(iq['i'][0]/iq['p0'][0]**2, 1, delta=0.075)
        iqfftw = pd.read_csv('hs_iq_fftw.csv')
        self.assertAlmostEqual(iqfftw['s'][1], 0.42828, delta=0.005)

        import matplotlib.pyplot as plt
        plt.scatter(iq['q'], iq['i']/iq['p0']**2, label='sq_all')
        plt.plot(grp.mean()['q'], grp.mean()['i']/grp.mean()['p0']**2, label='sq_av', color='black')
        plt.plot(iqfftw['q'], iqfftw['s'], label='sq fftw', color='red')
        plt.xlabel('q', fontsize=16)
        plt.ylabel('S', fontsize=16)
        plt.scatter(iq['q'], iq['i'], label='iq_all')
        plt.xlabel('q', fontsize=16)
        plt.ylabel('I', fontsize=16)

# run the simulation and, if complete, analyze.
def run():
    if args.task == 0:
        file_name = "hs_launch.txt"
        mc_hs(params, file_name=file_name)
        syscode ="../../../build/bin/fst < " + file_name + " > hs_launch.log", shell=True, executable='/bin/bash')
        syscode ="../../../build/bin/rst hs_checkpoint.fst", shell=True, executable='/bin/bash')
    if syscode == 0:
        unittest.main(argv=[''], verbosity=2, exit=False)
    return syscode

if __name__ == "__main__":
    if args.run_type == 0:
        syscode = run()
        if syscode != 0:
    elif args.run_type == 1:
        slurm_queue()"sbatch --array=0-10%1 slurm.txt | awk '{print $4}' >> launch_ids.txt", shell=True, executable='/bin/bash')
    elif args.run_type == 2:
        unittest.main(argv=[''], verbosity=2, exit=False)
        assert False  # unrecognized run_type