Port Distance Calculator

a README.py

#  Great circle distance calculations between selected Asian ports and selected ports on the West Coast of 
#  the Americas.
#
#  Using GeoDjango ORM to interact with PostGIS geography columns.
#
#  https://docs.djangoproject.com/en/dev/ref/contrib/gis/
#  http://postgis.refractions.net/docs/ch04.html#PostGIS_Geography

models.py

from django.contrib.gis.db import models

class Port(models.Model):
    name = models.CharField(max_length=100)
    location = models.PointField(geography=True)
    objects = models.GeoManager()

class AsiaPort(Port):
    objects = models.GeoManager()

class AmericaPort(Port):
    objects = models.GeoManager()

report.py

from ports.models import *

for asia_port in AsiaPort.objects.all():
    targets = AmericaPort.objects.all().distance(asia_port.location).order_by('distance')

    print('')
    print(asia_port.name.upper())
    print('==============')

    for target in targets:
        print('%s: %s miles' % (target.name, int(target.distance.mi)) ) 

seed_data.py

from ports.models import AsiaPort, AmericaPort

from django.contrib.gis.geos import Point

ASIA_POINTS = {
    'Busan': Point(129.075556, 35.179444, srid=4326),
    'Kobe': Point(135.2, 34.683333, srid=4326),
    'Tokyo': Point(139.75, 35.666667, srid=4326),
    'Shenzen': Point(113.883333, 22.5, srid=4326),
    'Shanghai': Point(121.5, 31.2, srid=4326),
    'Hong Kong': Point(114.166667, 22.25, srid=4326),
    'Tianjin': Point(117.785278, 38.976667, srid=4326),
    'Jakarta': Point(106.75, -6.133333, srid=4326),
    'Taipei': Point(121.633333, 25.033333, srid=4326),
    'Ho Chi Minh City': Point(106.681944, 10.769444, srid=4326),
}

AMERICAS_POINTS = {
    'Humboldt Bay': Point(-124.163611, 40.801944, srid=4326),
    'Tacoma': Point(-122.408333, 47.260278, srid=4326),
    'Oakland': Point(-122.284603, 37.795533, srid=4326),
    'Long Beach': Point(-118.216458, 33.754185, srid=4326),
    'Prince Rupert': Point(-130.327083, 54.312194, srid=4326),
    'Ensenada': Point(-116.626389, 31.850833, srid=4326),
}

AsiaPort.objects.all().delete()
AmericaPort.objects.all().delete()

for key, value in ASIA_POINTS.items():
    port = AsiaPort(
        name=key,
        location=value
    ).save()

for key, value in AMERICAS_POINTS.items():
    port = AmericaPort(
        name=key,
        location=value
    ).save()

z output of report.py

HO CHI MINH CITY
==============
Prince Rupert: 6862 miles
Tacoma: 7430 miles
Humboldt Bay: 7632 miles
Oakland: 7835 miles
Long Beach: 8186 miles
Ensenada: 8340 miles

JAKARTA
==============
Prince Rupert: 7857 miles
Tacoma: 8385 miles
Humboldt Bay: 8501 miles
Oakland: 8675 miles
Long Beach: 8995 miles
Ensenada: 9132 miles

SHENZEN
==============
Prince Rupert: 5926 miles
Tacoma: 6494 miles
Humboldt Bay: 6706 miles
Oakland: 6914 miles
Long Beach: 7268 miles
Ensenada: 7424 miles

BUSAN
==============
Prince Rupert: 4685 miles
Tacoma: 5243 miles
Humboldt Bay: 5441 miles
Oakland: 5648 miles
Long Beach: 6002 miles
Ensenada: 6158 miles

TOKYO
==============
Prince Rupert: 4272 miles
Tacoma: 4801 miles
Humboldt Bay: 4958 miles
Oakland: 5154 miles
Long Beach: 5501 miles
Ensenada: 5653 miles

TIANJIN
==============
Prince Rupert: 4850 miles
Tacoma: 5436 miles
Humboldt Bay: 5698 miles
Oakland: 5919 miles
Long Beach: 6279 miles
Ensenada: 6439 miles

KOBE
==============
Prince Rupert: 4492 miles
Tacoma: 5031 miles
Humboldt Bay: 5201 miles
Oakland: 5401 miles
Long Beach: 5750 miles
Ensenada: 5903 miles

SHANGHAI
==============
Prince Rupert: 5167 miles
Tacoma: 5734 miles
Humboldt Bay: 5947 miles
Oakland: 6156 miles
Long Beach: 6511 miles
Ensenada: 6668 miles

HONG KONG
==============
Prince Rupert: 5931 miles
Tacoma: 6498 miles
Humboldt Bay: 6707 miles
Oakland: 6915 miles
Long Beach: 7268 miles
Ensenada: 7424 miles

TAIPEI
==============
Prince Rupert: 5512 miles
Tacoma: 6065 miles
Humboldt Bay: 6248 miles
Oakland: 6449 miles
Long Beach: 6799 miles
Ensenada: 6953 miles