#!/usr/bin/env python
import sys
import urllib
def dms(d,m,s):
return d+m/60.+s/3600.
def parsedms(f):
"""
Imports a coordinates from tsv file and returns it as a list
"""
a=[]
for line in f:
t=line.rsplit("t")
lon=dms(int(t[0]),int(t[1]),int(t[2]))
lat=dms(int(t[3]),int(t[4]),int(t[5]))
a.append((-lon,lat))
return a
print >> sys.stderr, "loading river data"
river_file = urllib.urlopen("http://collincode.files.wordpress.com/2008/02/mississippi-river.txt")
print >> sys.stderr, "parsing river data"
river = parsedms(river_file)
def distance(Lon1,Lat1,Lon2,Lat2):
"""
Calculates the distance between two coordinates
Based on calcDistance in http://nmviewogc.cr.usgs.gov/javascript/aimsMap.js
"""
import math as Math
Lon1 = Lon1 * Math.pi / 180;
Lon2 = Lon2 * Math.pi / 180;
Lat1 = Lat1 * Math.pi / 180;
Lat2 = Lat2 * Math.pi / 180;
LonDist = Lon1-Lon2;
LatDist = Lat1-Lat2;
A = Math.pow(Math.sin(LatDist / 2),2) + Math.cos(Lat1) * Math.cos(Lat2) * Math.pow(Math.sin(LonDist /2),2);
C = 2 * Math.asin(Math.sqrt(A));
D = (3963.1676 - 13 * Math.sin((Lat1 + Lat2) / 2)) * C;
return D
def dist2river(lon,lat,river):
'returns the distance and closest point on the river to the point'
smallest = distance(river[0][0],river[0][1],lon,lat) #check against initial point
for point in river:
d = distance(point[0],point[1],lon,lat)
if d <= smallest: #see if this point is closer
thepoint=point
smallest=d
return smallest, thepoint
COLUMNS = (
(1, 2, 'state', str),
(8, 71, 'name', lambda x: str(x).strip()),
(72, 80, 'pop', int),
(81, 89, 'houses', long),
(118, 129, 'land', float),
(130, 141, 'water', float),
(142, 151, 'lat', float),
(152, 162, 'lon', float),
)
def parse_line(line):
return dict([(name, klass(line[s-1:e])) for s, e, name, klass in COLUMNS])
def parse_data(county_file):
for line in county_file:
if line:
yield parse_line(line)
print >> sys.stderr, "loading county data"
county_file = urllib.urlopen("http://www.census.gov/tiger/tms/gazetteer/county2k.txt")
print >> sys.stderr, "parsing county data"
data = []
for county in parse_data(county_file):
if county['name'].endswith(' County') or county['name'].endswith(' Parish'):
county['name'] = county['name'][:-len(' County')]
data.append(county)
print >> sys.stderr, "calculating distances to river"
distances = {}
for county in data:
key = "%s, %s" % (county['name'], county['state'])
key = key.lower()
dist = dist2river(county['lon'], county['lat'], river)[0]
if dist < 305:
distances[key] = dist
print >> sys.stderr, "processing your data"
def runfile(i, o):
for line in i:
line = line.strip("n")
columns = line.split('t')
county = columns[0]
key = county.strip().lower()
if key in distances:
print >> o, "%.3ft%s" % (distances[key], line)
import os
for x in os.listdir('.'):
if x.startswith('b'):
print "running %s" % x
runfile(file(x), file('o' + x, 'w'))
