''' Purpose: determine a rough estimate of the geocenter of the
        continental USA
'''

# get access to CS 1112 web-based data support
import url

# name the location of the data repository
CSV_WEB_FOLDER = 'http://www.cs.virginia.edu/~cs1112/datasets/csv/'
USA_DATASET    = CSV_WEB_FOLDER + 'continental-usa.csv'

# get the dataset of interest
dataset = url.get_and_parse_dataset( USA_DATASET )

# determine webfile header and location data
header    = dataset[ 0 ]
locations = dataset[ 1: ]

num_of_locations = len( locations )

# determine geocenter

# start by getting the lists of latitudes and longitudes from the data set
latitudes = []
longitudes = []
for row in locations:
    zipcode, town, state, latitude, longitude = row 
    latitudes.append( latitude ) 
    longitudes.append( longitude )

# now sort the lists
latitudes = sorted( latitudes )
longitudes = sorted( longitudes )

# find the median latitude and longitude
mid_index = num_of_locations // 2
median_latitude  = latitudes[ mid_index ]
median_longitude = longitudes[ mid_index ]

# use them to get the median
median = ( median_latitude, median_longitude )

# print result
print( median )