Initial implementation of IGRA data parser

lib/xmet/igra.py

@@ -0,0 +1,141 @@
+import io
+import re
+import datetime
+import shapely
+
+from xmet.coord    import COORD_SYSTEM
+from xmet.sounding import Sounding, SoundingSample
+
+RE_HEADER = re.compile(r'''
+      ^ (?P<headrec>\#)
+        (?P<id>[A-Z0-9]{11})
+    [ ] (?P<year>\d{4})
+    [ ] (?P<month>\d{2})
+    [ ] (?P<day>\d{2})
+    [ ] (?P<hour>\d{2})
+    [ ] (?P<relhour>\d{2}) (?P<relmin>\d{2})
+    [ ] (?P<numlev>[0-9\ ]{4})
+    [ ] (?P<p_src>.{8})
+    [ ] (?P<np_src>.{8})
+    [ ] (?P<lat>[0-9 ]{7})
+    [ ] (?P<lon>[0-9 ]{8})
+    $
+''', re.X)
+
+RE_SAMPLE = re.compile(r'''
+      ^ (?P<lvltyp1>\d)
+        (?P<lvltyp2>\d)
+    [ ] (?P<etime>[0-9 \-]{5})
+        (?P<press>[0-9 \-]{7})
+        (?P<pflag>[AB ])
+        (?P<gph>[0-9 \-]{5})
+        (?P<zflag>[AB ])
+        (?P<temp>[0-9 \-]{5})
+        (?P<tflag>[AB ])
+        (?P<rh>[0-9 \-]{5})
+    [ ] (?P<dpdp>[0-9 \-]{5})
+    [ ] (?P<wdir>[0-9 \-]{5})
+    [ ] (?P<wspd>[0-9 \-]{5})
+''', re.X)
+
+def etime_to_seconds(etime: str) -> int:
+    if etime == '-8888' or etime == '-9999':
+        return
+
+    return 60 * int(etime[0:2]) + int(etime[2:])
+
+def parse_num(num: str, scale: float) -> float:
+    if num == '-8888' or num == '-9999':
+        return
+
+    return int(num) * scale
+
+class IGRAReaderException(Exception):
+    ...
+
+class IGRAReader():
+    def __init__(self, fh: io.TextIOBase):
+        self.fh = fh
+
+    def read_sample(self) -> SoundingSample:
+        line = self.fh.readline()
+
+        if line == '':
+            return
+
+        match = RE_SAMPLE.match(line)
+
+        if match is None:
+            raise IGRAReaderException(f"Invalid sample line {line}")
+
+        sample = SoundingSample()
+        sample.elapsed     = etime_to_seconds(match['etime'])
+        sample.pressure    = parse_num(match['press'], 0.01)
+        sample.pressure_qa = match['pflag']
+        sample.height      = parse_num(match['gph'], 1.0)
+        sample.height_qa   = match['zflag']
+        sample.temp        = parse_num(match['temp'], 0.1)
+        sample.temp_qa     = match['tflag']
+        sample.humidity    = parse_num(match['rh'], 0.1)
+        sample.dewpoint    = parse_num(match['dpdp'], 0.1)
+        sample.wind_dir    = parse_num(match['wdir'], 1.0)
+        sample.wind_speed  = parse_num(match['wspd'], 0.1)
+
+        return sample
+
+    def read(self) -> Sounding:
+        line = self.fh.readline()
+
+        if line == '':
+            return
+
+        line = line.rstrip()
+
+        match = RE_HEADER.match(line)
+
+        if match is None:
+            raise IGRAReaderException(f"Invalid record line {line}")
+
+        sounding = Sounding()
+        sounding.station = match['id']
+
+        date = datetime.datetime(
+            year  = int(match['year']),
+            month = int(match['month']),
+            day   = int(match['day'])
+        )
+
+        timestamp         = date.astimezone(datetime.UTC)
+        timestamp_release = date.astimezone(datetime.UTC)
+
+        if match['hour'] != '99':
+            timestamp += datetime.timedelta(hours=int(match['hour']))
+
+        timestamp_release += datetime.timedelta(hours=int(match['relhour']))
+
+        if match['relmin'] != '99':
+            timestamp_release += datetime.timedelta(minutes=int(match['relmin']))
+
+        lat = int(match['lat']) / 1000.0
+        lon = int(match['lon']) / 1000.0
+
+        sounding.timestamp_observed   = timestamp
+        sounding.timestamp_released   = timestamp_release
+        sounding.data_source_pressure = match['p_src']
+        sounding.data_source_other    = match['np_src']
+        sounding.coord                = shapely.Point(lon, lat, COORD_SYSTEM)
+        sounding.samples              = list()
+
+        count = int(match['numlev'])
+
+        while count > 0:
+            sample = self.read_sample()
+
+            if sample is None:
+                break
+
+            sounding.samples.append(sample)
+
+            count -= 1
+
+        return sounding