[GIS] Calculating distance between latitude and longitude Python and CSV

distancelatitude longitudepython

I wanting to compare the distance between two sets of lat/long and
I need help inputting my lat/long fields into the Haversine formula.

I am able to print my two sets of lat/longs (print floats1, floats2, floats3, and floats4). I am unsure how to take these variables and use them as my inputs for the Haversine definition.

I was able to find similar code on GIS Stack Exchange, but I am fairly new to python and having some trouble.

import csv
import math

def haversine(lon1, lat1, lon2, lat2):
    """
    Calculate the great circle distance between two points
    on the earth (specified in decimal degrees).
    Source: http://gis.stackexchange.com/a/56589/15183
    """
    # convert decimal degrees to radians
    lon1, lat1, lon2, lat2 = map(math.radians, [lon1, lat1, lon2, lat2])
    # haversine formula
    dlon = lon2 - lon1
    dlat = lat2 - lat1
    a = math.sin(dlat/2)**2 + math.cos(lat1) * math.cos(lat2) * math.sin(dlon/2)**2
    c = 2 * math.asin(math.sqrt(a))
    km = 6367 * c
    return km

with open(r'PathtoFile.csv', 'rb') as f1:
    reader1 = csv.reader(f1, delimiter=',', quoting=csv.QUOTE_NONE)
    header1 = reader1.next()
    for row1 in reader1:
        floats1 = map(float, row1[16:]) #lon1
        floats2 = map(float, row1[17:]) #lat1
        floats3 = map(float, row1[18:]) #lon2
        floats4 = map(float, row1[19:]) #lat2
        print(floats1)
        print(floats2)
        print(floats3)
        print(floats4)
        print haversine(floats1[1],floats1[0],floats3[1],floats4[0])

Best Answer

I don't have enough reputation to post this as a comment, but since nobody else has contributed yet, I'll just put this here. Are you sure you are passing your lat/longs as numbers and not strings?

Maybe try something like this just to make sure:

print haversine(float(floats1[1]),float(floats1[0]),float(floats3[1]),float(floats4[0]))

Also, is there a reason why you have an index on your values going to the function? Should it not just be:

print haversine(float(floats1),float(floats2),float(floats3),float(floats4))

I also noticed you reference floats1 twice in the call to the function.

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