airports with the same IATA code active at the same time

gistfile1.py

from collections import defaultdict
from itertools import tee, izip
import datetime

airports = defaultdict(list)


# read all period from / to for all airports
with open("optd_por_public.csv") as fin:
    for line in fin:
        items = line.split('^')
        iata_code = items[0]
        start = items[13] if items[13] != "" else "1900-01-01"
        end = items[14] if items[14] != "" else "2999-12-31"
        por_type = items[-5]
        
        if 'A' in por_type and iata_code != "ZZZ":
            airports[iata_code].append((start, end))
        

# filter those with more than one entry and sort by start & end date
airports = {k: sorted(v) for k, v in airports.iteritems() if len(v) > 1}

def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return izip(a, b)

def check_overlap(l):
    for (s1, e1), (s2, e2) in pairwise(l):
        if e1 > s2: return True
    return False

# get those with an overlap
airports = {k: v for k, v in airports.iteritems() if check_overlap(v)}


for k, v in airports.iteritems():
    print k, " and ".join(["%s to %s" % (s, e) for s, e in v])