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

# get access to web-based data support
import url

# specify dataset web location
CSV_WEB_FOLDER = 'http://www.cs.virginia.edu/~cs1112/datasets/csv/'

# dataset name
CONTINENTAL_DATASET = 'continental-usa.csv'

# set link
link    = CSV_WEB_FOLDER + CONTINENTAL_DATASET

# get the dataset of interest
locations = url.get_dataset( link )    # get_dataset( link ) is another function in url
                                       # you give it a web link
                                       # returns a formatted dataset/table
                                       # so locations is a list of lists
                                       # each row is a location of a town, with 4 columns

# to use a function in a module like url: module_name.function_name()

# determine geocenter

# a loop that might be helpful for solving the problem
# for each location in locations dataset
# strategy 1: find min and max latitude and longitude --> take average of each
#   so we need a list of latitudes and a list of longitudes
# strategy 2: find average of latitudes and longitudes
#   also need a list of latitudes and longitudes

latitudes = []
longitudes = []
for location in locations :
    zipcode, town, state, latitude, longitude = location
    # we know each location has 4 things in it, hence why we
    # could assign 4 variables at the same time

    # build up the 2 accumulator lists
    latitudes.append( latitude )
    longitudes.append( longitude )

# print( latitudes )
# print( longitudes )

# strategy 1
min_lat = min( latitudes )
min_long = min( longitudes )

max_lat = max( latitudes )
max_long = max( longitudes )

min_max_lat_avg = ( min_lat + max_lat ) / 2
min_max_long_avg = ( min_long + max_long ) / 2

print( min_max_lat_avg, min_max_long_avg )

# strategy 2
avg_lat = sum( latitudes ) / len( latitudes )
avg_long = sum( longitudes ) / len( longitudes )
print( avg_lat, avg_long )