csiborgtools/scripts/field_bulk.py

# Copyright (C) 2023 Richard Stiskalek
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
"""
A script to calculate the enclosed mass or bulk flow at different distances
from the center of the box directly from the particles. Note that the velocity
of an observer is not being subtracted from the bulk flow.

The script is not parallelized in any way but it should not take very long, the
main bottleneck is reading the data from disk.
"""
from argparse import ArgumentParser
from os.path import join
from gc import collect

import csiborgtools
import numpy
from tqdm import tqdm

from datetime import datetime


###############################################################################
#                Read in information about the simulation                     #
###############################################################################


def t():
    return datetime.now()


def get_reader(simname, paths, nsim):
    """
    Get the appropriate snaspshot reader for the simulation.

    Parameters
    ----------
    simname : str
        Name of the simulation.
    paths : csiborgtools.read.Paths
        Paths object.
    nsim : int
        Simulation index.

    Returns
    -------
    reader : instance of csiborgtools.read.BaseSnapshot
        Snapshot reader.
    """
    if simname == "csiborg1":
        nsnap = max(paths.get_snapshots(nsim, simname))
        reader = csiborgtools.read.CSiBORG1Snapshot(nsim, nsnap, paths,
                                                    flip_xz=True)
    elif "csiborg2" in simname:
        kind = simname.split("_")[-1]
        reader = csiborgtools.read.CSiBORG2Snapshot(nsim, 99, kind, paths,
                                                    flip_xz=True)
    else:
        raise ValueError(f"Unknown simname: `{simname}`.")

    return reader


def get_particles(reader, boxsize, get_velocity=True, verbose=True):
    """
    Get the distance of particles from the center of the box and their masses.

    Parameters
    ----------
    reader : instance of csiborgtools.read.BaseSnapshot
        Snapshot reader.
    boxsize : float
        Box size in Mpc / h.
    get_velocity : bool, optional
        Whether to also return the velocity of particles.
    verbose : bool
        Verbosity flag.

    Returns
    -------
    dist : 1-dimensional array
        Distance of particles from the center of the box.
    mass : 1-dimensional array
        Mass of particles.
    vel : 2-dimensional array, optional
        Velocity of particles.
    """
    if verbose:
        print(f"{t()},: reading coordinates and calculating radial distance.")
    pos = reader.coordinates()
    dtype = pos.dtype
    pos -= boxsize / 2
    dist = numpy.linalg.norm(pos, axis=1).astype(dtype)
    del pos
    collect()

    if verbose:
        print(f"{t()}: reading masses.")
    mass = reader.masses()

    if get_velocity:
        if verbose:
            print(f"{t()}: reading velocities.")
        vel = reader.velocities().astype(dtype)

    if verbose:
        print(f"{t()}: sorting arrays.")
    indxs = numpy.argsort(dist)
    dist = dist[indxs]
    mass = mass[indxs]
    if get_velocity:
        vel = vel[indxs]

    del indxs
    collect()

    if get_velocity:
        return dist, mass, vel

    return dist, mass


###############################################################################
#                       Main & command line interface                         #
###############################################################################


def main_borg(args, folder):
    paths = csiborgtools.read.Paths(**csiborgtools.paths_glamdring)
    boxsize = csiborgtools.simname2boxsize(args.simname)
    nsims = paths.get_ics(args.simname)
    distances = numpy.linspace(0, boxsize / 2, 101)[1:]

    cumulative_mass = numpy.zeros((len(nsims), len(distances)))
    cumulative_volume = numpy.zeros((len(nsims), len(distances)))
    for i, nsim in enumerate(tqdm(nsims, desc="Simulations")):
        if args.simname == "borg1":
            reader = csiborgtools.read.BORG1Field(nsim)
            field = reader.density_field()
        elif args.simname == "borg2":
            reader = csiborgtools.read.BORG2Field(nsim)
            field = reader.density_field()
        else:
            raise ValueError(f"Unknown simname: `{args.simname}`.")

        cumulative_mass[i, :], cumulative_volume[i, :] = csiborgtools.field.field_enclosed_mass(  # noqa
            field, distances, boxsize)

    # Finally save the output
    fname = f"enclosed_mass_{args.simname}.npz"
    fname = join(folder, fname)
    numpy.savez(fname, enclosed_mass=cumulative_mass, distances=distances,
                enclosed_volume=cumulative_volume)


def main_csiborg(args, folder):
    paths = csiborgtools.read.Paths(**csiborgtools.paths_glamdring)
    boxsize = csiborgtools.simname2boxsize(args.simname)
    nsims = paths.get_ics(args.simname)
    distances = numpy.linspace(0, boxsize / 2, 501)[1:]

    # Initialize arrays to store the results
    cumulative_mass = numpy.zeros((len(nsims), len(distances)))
    mass135 = numpy.zeros(len(nsims))
    masstot = numpy.zeros(len(nsims))
    cumulative_velocity = numpy.zeros((len(nsims), len(distances), 3))

    for i, nsim in enumerate(tqdm(nsims, desc="Simulations")):
        reader = get_reader(args.simname, paths, nsim)
        rdist, mass, vel = get_particles(reader, boxsize,  verbose=False)

        # Calculate masses
        cumulative_mass[i, :] = csiborgtools.field.particles_enclosed_mass(
            rdist, mass, distances)
        mass135[i] = csiborgtools.field.particles_enclosed_mass(
            rdist, mass, [135])[0]
        masstot[i] = numpy.sum(mass)

        # Calculate velocities
        cumulative_velocity[i, ...] = csiborgtools.field.particles_enclosed_momentum(  # noqa
            rdist, mass, vel, distances)
        for j in range(3):  # Normalize the momentum to get velocity out of it.
            cumulative_velocity[i, :, j] /= cumulative_mass[i, :]

    # Finally save the output
    fname = f"enclosed_mass_{args.simname}.npz"
    fname = join(folder, fname)
    numpy.savez(fname, enclosed_mass=cumulative_mass, mass135=mass135,
                masstot=masstot, distances=distances,
                cumulative_velocity=cumulative_velocity)


if __name__ == "__main__":
    parser = ArgumentParser()
    parser.add_argument("--simname", type=str, help="Simulation name.",
                        choices=["csiborg1", "csiborg2_main", "csiborg2_varysmall", "csiborg2_random", "borg1", "borg2"])  # noqa
    args = parser.parse_args()

    folder = "/mnt/extraspace/rstiskalek/csiborg_postprocessing/field_shells"
    if "csiborg" in args.simname:
        main_csiborg(args, folder)
    elif "borg" in args.simname:
        main_borg(args, folder)
    else:
        raise ValueError(f"Unknown simname: `{args.simname}`.")