airdata-histogram

import matplotlib.pyplot as plt
import csv
import geo_distance #for calculating dist b/w lats. and longs.

d = open("airports.dat.txt")
latitudes = {}
longitudes = {}
distances = []
for row in csv.reader(d):
    airport_id = row[0]
    latitudes[airport_id] = float(row[6])
    longitudes[airport_id] = float(row[7])

distances = []
f = open("routes.dat")
for row in csv.reader(f):
    source_airport = row[3]
    dest_airport = row[5]
    if source_airport in latitudes and dest_airport in latitudes:
        source_lat = latitudes[source_airport]
        source_long = longitudes[source_airport]
        dest_lat = latitudes[dest_airport]
        dest_long = longitudes[dest_airport]
        distances.append(geo_distance.distance(source_lat,source_long,dest_lat,dest_long))
#print distances
plt.hist(distances, 100, facecolor='b')
plt.xlabel("Distance (km)")
plt.ylabel("Number of flights")