pireps.py

import datetime
from datetime import timezone
import re

NO_ICE = '\s*NEG\s*|\s*NONE\s*|\s*NEGATIVE\s*|\s*NO\s*'
ICE_LVL = '\d+-\d+|FL\d+-FL\d+'

# ICE Intensity: 0:No intensity report, 1:Trace, 2:Light, 3:Light Moderate, 4:Moderate, 5:Moderate Severe, 6:Severe
# NO/NEG -1
ICE_TRACE = '\s*TRACE\s*|\s*TRC\s*|\s*TR\s*'
ICE_LGT = '\s*LGT\s*|\s*LIGHT\s*|\s*LT\s*|\s*LGHT\s*|\s*LIT\s*|\s*LITE\s*|\s*LG\s*'
ICE_MOD = '\s*MOD\s*|\s*MDT\s*|\s*MODERATE\s*|\s*HEAVY\s*'
ICE_SVR = '\s*SVR\s*|\s*SEV\s*|\s*SEVERE\s*'

FLT_LVL = '/FL\s{0,1}\d+\s*'
ICE_RPT = '/IC'
ATYPE = '/TP'
RMK = '/RM'


# Returns icing, no_icing (no icing observed), neg-icing (icing expected, but not observed)
def pirep_icing(filename, lon_range=[-180, 180], lat_range=[-63, 63]):

    # HEADER: VALID,URGENT,AIRCRAFT,REPORT,LAT,LON

    ice_dict = {}
    neg_ice_dict = {}
    no_ice_dict = {}

    cnt_ice = 0
    cnt_no_ice = 0
    cnt_neg_ice = 0

    with open(filename) as file:
        for idx, line in enumerate(file):
            toks = line.split(',')
            if toks[0] == 'VALID':  # Skip headers (concatenated files)
                continue
            if len(toks) != 6:  # Check for line format error
                continue

            report = toks[3]
            try:
                lat = float(toks[4])
                lon = float(toks[5])
            except Exception:
                continue

            if lon < lon_range[0] or lon > lon_range[1]:
                continue
            if lat < lat_range[0] or lat > lat_range[1]:
                continue

            # Flight level
            so = re.search(FLT_LVL, report)
            if so is None:
                continue
            else:
                fl = so.group()
                fl = (fl[3:].rstrip()).lstrip()
                if fl.isnumeric():
                    fl = float(fl) * 100 * 0.3048  # conv flight level to meters
                else:
                    continue

            dto = datetime.datetime.strptime(toks[0], '%Y%m%d%H%M').replace(tzinfo=timezone.utc)
            timestmp = dto.timestamp()

            # Icing
            ii = report.find('/IC')
            if ii >= 0:
                ice_str = report[ii+3:]
                ri = ice_str.find('/RM')

                if ri >= 0:
                    ice_str = ice_str[:ri]
                else:
                    ri = ice_str.find(',')
                    if ri >= 0:
                        ice_str = ice_str[:ri]
                ice_str = ice_str.lstrip()
                if ice_str.find('N/A') >= 0:
                    continue

                if len(re.findall(NO_ICE, ice_str)) != 0:
                    rpts = neg_ice_dict.get(timestmp)
                    tup = (lat, lon, fl, -1, cnt_neg_ice, ice_str)
                    cnt_neg_ice += 1
                    if rpts is None:
                        rpts = []
                        rpts.append(tup)
                        neg_ice_dict[timestmp] = rpts
                    else:
                        rpts.append(tup)
                else:
                    so = re.search(ICE_LVL, ice_str)
                    if so is not None:
                        lvl_a, lvl_b = so.group().split('-')
                        if lvl_a.find('FL') >= 0:
                            lvl_a = float(lvl_a[2:]) * 100 * 0.3048
                            lvl_b = float(lvl_b[2:]) * 100 * 0.3048
                        else:
                            lvl_a = float(lvl_a) * 100 * 0.3048
                            lvl_b = float(lvl_b) * 100 * 0.3048

                        fl = max(lvl_a, lvl_b)

                    if fl > 15000.0:
                        continue

                    # Intensity
                    I = 0
                    so = re.search(ICE_TRACE, ice_str)
                    if so is not None:
                        I = 1
                    else:
                        so = re.search(ICE_LGT, ice_str)
                        if so is not None:
                            so = re.search(ICE_MOD, ice_str)
                            if so is not None:
                                I = 3
                            else:
                                I = 2
                        else:
                            so = re.search(ICE_MOD, ice_str)
                            if so is not None:
                                so = re.search(ICE_SVR, ice_str)
                                if so is not None:
                                    I = 5
                                else:
                                    I = 4
                            else:
                                so = re.search(ICE_SVR, ice_str)
                                if so is not None:
                                    I = 6

                    rpts = ice_dict.get(timestmp)
                    tup = (lat, lon, fl, I, cnt_ice, ice_str)
                    cnt_ice += 1
                    if rpts is None:
                        rpts = []
                        rpts.append(tup)
                        ice_dict[timestmp] = rpts
                    else:
                        rpts.append(tup)
            else:
                rpts = no_ice_dict.get(timestmp)
                tup = (lat, lon, fl, -1, cnt_no_ice, 'no observed icing')
                cnt_no_ice += 1
                if rpts is None:
                    rpts = []
                    rpts.append(tup)
                    no_ice_dict[timestmp] = rpts
                else:
                    rpts.append(tup)

    return ice_dict, no_ice_dict, neg_ice_dict