Add missing dep

satellite_tle/__init__.py

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+from .fetch_tle import * # noqa
+from .fetch_tles import * # noqa

satellite_tle/fetch_tle.py

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+import csv
+from lxml import html
+import requests
+import pkg_resources
+
+SOURCES_LIST = pkg_resources.resource_filename('satellite_tle', 'sources.csv')
+
+
+def get_tle_sources():
+    '''
+    Returns a list of (source, url)-tuples for well-known TLE sources.
+    '''
+
+    sources = []
+
+    with open(SOURCES_LIST) as csvfile:
+        csv_reader = csv.reader(csvfile,
+                                delimiter=',',
+                                quotechar='\'',
+                                quoting=csv.QUOTE_NONNUMERIC)
+        for row in csv_reader:
+            source, url = row
+            sources.append((source, url))
+
+    return sources
+
+
+def fetch_tle_from_celestrak(norad_cat_id):
+    '''
+    Returns the TLE for a given norad_cat_id as currently available from CelesTrak.
+    Raises IndexError if no data is available for the given norad_cat_id.
+    '''
+
+    r = requests.get('https://www.celestrak.com/satcat/tle.php?CATNR={}'.format(norad_cat_id))
+    page = html.fromstring(r.text)
+
+    tle = page.xpath('//pre/text()')[0].split('\n')
+    if tle[1].strip() == 'No TLE found':
+        raise LookupError
+
+    return tle[1].strip(), tle[2].strip(), tle[3].strip()
+
+
+def fetch_tles_from_url(url):
+    '''
+    Downloads the TLE set from the given url.
+    Returns a dictionary of the form {norad_id1: tle1, norad_id2: tle2} for all TLEs found.
+    tleN is returned as list of three strings: [satellite_name, line1, line2].
+    '''
+
+    r = requests.get(url)
+
+    tles = dict()
+    l0 = ''
+    l1 = ''
+    lines = r.text.splitlines()
+    for l in lines[:-1]:
+        if l[0] == '2':
+            norad_cat_id = int(l1[2:7].encode('ascii'))
+            tles[norad_cat_id] = (l0.strip(), l1, l)
+        l0 = l1
+        l1 = l
+
+    return tles

satellite_tle/fetch_tles.py

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+from __future__ import print_function
+
+from sgp4.earth_gravity import wgs72
+from sgp4.io import twoline2rv
+
+from . import get_tle_sources, fetch_tles_from_url, fetch_tle_from_celestrak
+
+
+def fetch_tles(requested_norad_ids):
+    '''
+    Returns the most recent TLEs found for the requested satellites
+    available via Celestrak, CalPoly and AMSAT.
+    '''
+
+    # List of 2-tuples of the form (source, tle)
+    # source is a human-readable string
+    # tle is a 3-tuple of strings
+    tles = dict()
+
+    def update_tles(source, tle):
+        if norad_id not in requested_norad_ids:
+            # Satellite not requested,
+            # skip.
+            return
+
+        if norad_id not in tles.keys():
+            # Satellite requested and first occurence in the downloaded data,
+            # store new TLE.
+            #print('Found {}'.format(norad_id))
+            tles[norad_id] = source, tle
+            return
+
+        # There are multiple TLEs for this satellite available.
+        # Parse and compare epoch of both TLEs and choose the most recent one.
+        current_sat = twoline2rv(tles[norad_id][1][1], tles[norad_id][1][2], wgs72)
+        new_sat = twoline2rv(tle[1], tle[2], wgs72)
+        if new_sat.epoch > current_sat.epoch:
+            # Found a more recent TLE than the current one,
+            # store the new TLE.
+
+            tles[norad_id] = source, tle
+
+    # Fetch TLE sets from well-known TLE sources
+    sources = get_tle_sources()
+
+    for source, url in sources:
+        #print('Fetch from {}'.format(url))
+        new_tles = fetch_tles_from_url(url=url)
+
+        for norad_id, tle in new_tles.items():
+            update_tles(source, tle)
+
+    # Try fetching missing sats from another Celestrak endoint
+    missing_norad_ids = set(requested_norad_ids) - set(tles.keys())
+
+    for norad_id in missing_norad_ids:
+        try:
+            #print('Fetching {} from Celestrak (satcat):'.format(norad_id), end='')
+            tle = fetch_tle_from_celestrak(norad_id)
+            #print(' ok, ', end='')
+            update_tles('Celestrak (satcat)', tle)
+        except LookupError:
+            #print(' failed.')
+            continue
+
+    return tles

satellite_tle/sources.csv

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+'CalPoly','http://mstl.atl.calpoly.edu/~ops/keps/kepler.txt'
+'AMSAT','https://www.amsat.org/amsat/ftp/keps/current/nasabare.txt'
+'Celestrak (tle-new)','https://www.celestrak.com/NORAD/elements/tle-new.txt'
+'Celestrak (stations)','https://www.celestrak.com/NORAD/elements/stations.txt'
+'Celestrak (visual)','https://www.celestrak.com/NORAD/elements/visual.txt'
+'Celestrak (1999-025)','https://www.celestrak.com/NORAD/elements/1999-025.txt'
+'Celestrak (iridium-33-debris)','https://www.celestrak.com/NORAD/elements/iridium-33-debris.txt'
+'Celestrak (cosmos-2251-debris)','https://www.celestrak.com/NORAD/elements/cosmos-2251-debris.txt'
+'Celestrak (2012-044)','https://www.celestrak.com/NORAD/elements/2012-044.txt'
+'Celestrak (weather)','https://www.celestrak.com/NORAD/elements/weather.txt'
+'Celestrak (noaa)','https://www.celestrak.com/NORAD/elements/noaa.txt'
+'Celestrak (goes)','https://www.celestrak.com/NORAD/elements/goes.txt'
+'Celestrak (resource)','https://www.celestrak.com/NORAD/elements/resource.txt'
+'Celestrak (sarsat)','https://www.celestrak.com/NORAD/elements/sarsat.txt'
+'Celestrak (dmc)','https://www.celestrak.com/NORAD/elements/dmc.txt'
+'Celestrak (tdrss)','https://www.celestrak.com/NORAD/elements/tdrss.txt'
+'Celestrak (argos)','https://www.celestrak.com/NORAD/elements/argos.txt'
+'Celestrak (planet)','https://www.celestrak.com/NORAD/elements/planet.txt'
+'Celestrak (spire)','https://www.celestrak.com/NORAD/elements/spire.txt'
+'Celestrak (geo)','https://www.celestrak.com/NORAD/elements/geo.txt'
+'Celestrak (intelsat)','https://www.celestrak.com/NORAD/elements/intelsat.txt'
+'Celestrak (ses)','https://www.celestrak.com/NORAD/elements/ses.txt'
+'Celestrak (iridium)','https://www.celestrak.com/NORAD/elements/iridium.txt'
+'Celestrak (iridium-NEXT)','https://www.celestrak.com/NORAD/elements/iridium-NEXT.txt'
+'Celestrak (orbcomm)','https://www.celestrak.com/NORAD/elements/orbcomm.txt'
+'Celestrak (globalstar)','https://www.celestrak.com/NORAD/elements/globalstar.txt'
+'Celestrak (amateur)','https://www.celestrak.com/NORAD/elements/amateur.txt'
+'Celestrak (other-comm)','https://www.celestrak.com/NORAD/elements/other-comm.txt'
+'Celestrak (gorizont)','https://www.celestrak.com/NORAD/elements/gorizont.txt'
+'Celestrak (raduga)','https://www.celestrak.com/NORAD/elements/raduga.txt'
+'Celestrak (molniya)','https://www.celestrak.com/NORAD/elements/molniya.txt'
+'Celestrak (gps-ops)','https://www.celestrak.com/NORAD/elements/gps-ops.txt'
+'Celestrak (glo-ops)','https://www.celestrak.com/NORAD/elements/glo-ops.txt'
+'Celestrak (galileo)','https://www.celestrak.com/NORAD/elements/galileo.txt'
+'Celestrak (beidou)','https://www.celestrak.com/NORAD/elements/beidou.txt'
+'Celestrak (sbas)','https://www.celestrak.com/NORAD/elements/sbas.txt'
+'Celestrak (nnss)','https://www.celestrak.com/NORAD/elements/nnss.txt'
+'Celestrak (musson)','https://www.celestrak.com/NORAD/elements/musson.txt'
+'Celestrak (science)','https://www.celestrak.com/NORAD/elements/science.txt'
+'Celestrak (geodetic)','https://www.celestrak.com/NORAD/elements/geodetic.txt'
+'Celestrak (engineering)','https://www.celestrak.com/NORAD/elements/engineering.txt'
+'Celestrak (education)','https://www.celestrak.com/NORAD/elements/education.txt'
+'Celestrak (military)','https://www.celestrak.com/NORAD/elements/military.txt'
+'Celestrak (radar)','https://www.celestrak.com/NORAD/elements/radar.txt'
+'Celestrak (cubesat)','https://www.celestrak.com/NORAD/elements/cubesat.txt'
+'Celestrak (other)','https://www.celestrak.com/NORAD/elements/other.txt'