The Skyfield OOM testing script from my Satellite Calculator Repo

test_oom.py

"""
A minimal working example of using tle, oom xml, and oom csv with the Skyfield Python Library

Licensed under the MIT license
Copyright (c) 2024 Juniper Foote
"""

from enum import Enum
from pathlib import Path
from urllib.request import urlopen

from sgp4 import omm
from sgp4.api import Satrec
from skyfield.api import EarthSatellite, load


class FileGuess(Enum):
    csv = ["OBJECT_NAME", ",", "OBJECT_ID"]
    xml = ["<?xml"]
    tle = [""]


def guess_type(file: Path) -> FileGuess:
    with open(file) as f:
        first_line = f.readline()
    file_type = None
    for test in FileGuess:
        if all(map(lambda x: x in first_line, test.value)):
            file_type = test
            break
    return file_type


def main(ifmt: str = "tle"):
    omm_parsers = {FileGuess.csv: omm.parse_csv, FileGuess.xml: omm.parse_xml}

    ts = load.timescale()
    active = Path(f"active.{ifmt}")

    if not active.exists():
        data = urlopen(
            f"https://celestrak.org/NORAD/elements/gp.php?GROUP=active&FORMAT={ifmt}"
        )
        active.write_bytes(data.read())


    ext = guess_type(active)

    sats = []

    if ext == FileGuess.tle:
        sats = load.tle_file(str(active))
    else:
        with open(active) as f:
            for fields in omm_parsers[ext](f):
                sat = Satrec()
                omm.initialize(sat, fields)
                nsat = EarthSatellite.from_satrec(sat, ts)
                nsat.name = fields["OBJECT_NAME"]
                sats.append(nsat)

    print(sats)


if __name__ == "__main__":
    main("tle")
    main("xml")
    main("csv")