DZone Snippets: location code

Location queries for a model

ajturner (Andrew Turner) — Wed, 12 Apr 2006 05:46:45 GMT

// These are class functions which are useful for finding locations in a database
// when PostGIS is not available (when using MySQL for example)



def self.deg2rad(deg)

	(deg * Math::PI / 180)

end



def self.rad2deg(rad)

	(rad * 180 / Math::PI)

end



def self.acos(rad)

	Math.atan2(Math.sqrt(1 - rad**2), rad)

end



def self.distance_in_miles(loc1, loc2)

	lat1 = loc1.latitude

	lon1 = loc1.longitude

	lat2 = loc2.latitude

	lon2 = loc2.longitude

	theta = lon1 - lon2

	

	dist = Math.sin(self.deg2rad(lat1)) * Math.sin(deg2rad(lat2)) 

		+ Math.cos(self.deg2rad(lat1)) * Math.cos(self.deg2rad(lat2)) * Math.cos(deg2rad(theta))

	

	dist = self.rad2deg(self.acos(dist))

	

	(dist * 60 * 1.1515).round #distance in miles

end



def miles_to(location)

	Location.distance_in_miles(self, location)

end



def self.locationArea(location, miles)

	radius = miles.to_f

	latR = radius / ((6076 / 5280) * 60)

	lonR = radius / (((Math.cos(location.latitude * Math::PI / 180) * 6076) / 5280) * 60)

	

	{

		:min_latitude => location.latitude - latR,

		:min_longitude => location.longitude - lonR,

		:max_latitude => location.latitude + latR,

		:max_longitude => location.longitude + lonR

	}

end



def self.location_ids_in_range(location, miles)

	la = Location.locationArea(location, miles)

	Location.find(:all,

		:select => "locations.id",

		:conditions => ["locations.latitude <= ? and locations.latitude >= ? " + \

			" AND locations.longitude >= ? and locations.longitude <= ?",

			la[:max_latitude], la[:min_latitude], la[:min_longitude], la[:max_longitude]

		]

	).collect { |l| l.id }

end



def self.locations_in_range(location, miles)

	la = Location.locationArea(location, miles)

	Location.find(:all,

		:conditions => ["locations.latitude <= ? and locations.latitude >= ? " + \

			" AND locations.longitude >= ? and locations.longitude <= ?",

			la[:max_latitude], la[:min_latitude], la[:min_longitude], la[:max_longitude]

		]

	)

end

Export a GoogleEarth KML file to CSV output

ajturner (Andrew Turner) — Sat, 25 Mar 2006 18:56:47 GMT

# Parses a GoogleEarth KML file and writes the pertinent data to a CSV file

#
#
#
# Folder Name
# 1
#
# ... Screen Overlays
#
#
# Document Name
# 1
#
# ... Schema Def ...
#
#
#
# FolderName
#
# Location name 1
#
# #khStyle16037
#
# relativeToGround
# -81.85829063169155,29.12257052899974,100
#
# Column 1 data
# Column 2 data
#
#
# Location name 2
#
# #khStyle16037
#
# relativeToGround
# -81.85829063169155,29.12257052899974,100
#
# Column 1 data
# Column 2 data
#
#
# ... More Locations ...
#
#
#
#



require "rexml/document"

include REXML

kmlroot = (Document.new File.new "data.kml").root

nodes = kmlroot.elements.to_a("//Location")



begin

	f = File.open("data.csv", "w")

	f << "id,column1,column2,latitude,longitude"\n"

	id = 1

	nodes.each { |node|

		column1 = node.elements["column1"].text

		column2 = node.elements["column2"].text

		coords = node.elements["Point"].elements["coordinates"].text.split(",")

		f << [id, column1, column2, coords[1], coords[0] ].join(",") << "\n"

		id += 1

	}

ensure

	f.close

end

US State Abbreviations to Full name

ajturner (Andrew Turner) — Sat, 25 Mar 2006 18:47:19 GMT

# US State abbreviations to full name
# state_name = state_abbr.[]("MI")



state_abbr = {

  'AL' => 'Alabama',

  'AK' => 'Alaska',

  'AS' => 'America Samoa',

  'AZ' => 'Arizona',

  'AR' => 'Arkansas',

  'CA' => 'California',

  'CO' => 'Colorado',

  'CT' => 'Connecticut',

  'DE' => 'Delaware',

  'DC' => 'District of Columbia',

  'FM' => 'Micronesia1',

  'FL' => 'Florida',

  'GA' => 'Georgia',

  'GU' => 'Guam',

  'HI' => 'Hawaii',

  'ID' => 'Idaho',

  'IL' => 'Illinois',

  'IN' => 'Indiana',

  'IA' => 'Iowa',

  'KS' => 'Kansas',

  'KY' => 'Kentucky',

  'LA' => 'Louisiana',

  'ME' => 'Maine',

  'MH' => 'Islands1',

  'MD' => 'Maryland',

  'MA' => 'Massachusetts',

  'MI' => 'Michigan',

  'MN' => 'Minnesota',

  'MS' => 'Mississippi',

  'MO' => 'Missouri',

  'MT' => 'Montana',

  'NE' => 'Nebraska',

  'NV' => 'Nevada',

  'NH' => 'New Hampshire',

  'NJ' => 'New Jersey',

  'NM' => 'New Mexico',

  'NY' => 'New York',

  'NC' => 'North Carolina',

  'ND' => 'North Dakota',

  'OH' => 'Ohio',

  'OK' => 'Oklahoma',

  'OR' => 'Oregon',

  'PW' => 'Palau',

  'PA' => 'Pennsylvania',

  'PR' => 'Puerto Rico',

  'RI' => 'Rhode Island',

  'SC' => 'South Carolina',

  'SD' => 'South Dakota',

  'TN' => 'Tennessee',

  'TX' => 'Texas',

  'UT' => 'Utah',

  'VT' => 'Vermont',

  'VI' => 'Virgin Island',

  'VA' => 'Virginia',

  'WA' => 'Washington',

  'WV' => 'West Virginia',

  'WI' => 'Wisconsin',

  'WY' => 'Wyoming'

}

Average US State Locations

ajturner (Andrew Turner) — Sat, 25 Mar 2006 18:44:20 GMT

# A hash table of average US State Locations (latitude, longitude)
# MI_Location = state_locations.[]("MI")



state_locations = {

  'AK' => [61.3850,-152.2683],

  'AL' => [32.7990,-86.8073],

  'AR' => [34.9513,-92.3809],

  'AS' => [14.2417,-170.7197],

  'AZ' => [33.7712,-111.3877],

  'CA' => [36.1700,-119.7462],

  'CO' => [39.0646,-105.3272],

  'CT' => [41.5834,-72.7622],

  'DC' => [38.8964,-77.0262],

  'DE' => [39.3498,-75.5148],

  'FL' => [27.8333,-81.7170],

  'GA' => [32.9866,-83.6487],

  'HI' => [21.1098,-157.5311],

  'IA' => [42.0046,-93.2140],

  'ID' => [44.2394,-114.5103],

  'IL' => [40.3363,-89.0022],

  'IN' => [39.8647,-86.2604],

  'KS' => [38.5111,-96.8005],

  'KY' => [37.6690,-84.6514],

  'LA' => [31.1801,-91.8749],

  'MA' => [42.2373,-71.5314],

  'MD' => [39.0724,-76.7902],

  'ME' => [44.6074,-69.3977],

  'MI' => [43.3504,-84.5603],

  'MN' => [45.7326,-93.9196],

  'MO' => [38.4623,-92.3020],

  'MP' => [14.8058,145.5505],

  'MS' => [32.7673,-89.6812],

  'MT' => [46.9048,-110.3261],

  'NC' => [35.6411,-79.8431],

  'ND' => [47.5362,-99.7930],

  'NE' => [41.1289,-98.2883],

  'NH' => [43.4108,-71.5653],

  'NJ' => [40.3140,-74.5089],

  'NM' => [34.8375,-106.2371],

  'NV' => [38.4199,-117.1219],

  'NY' => [42.1497,-74.9384],

  'OH' => [40.3736,-82.7755],

  'OK' => [35.5376,-96.9247],

  'OR' => [44.5672,-122.1269],

  'PA' => [40.5773,-77.2640],

  'PR' => [18.2766,-66.3350],

  'RI' => [41.6772,-71.5101],

  'SC' => [33.8191,-80.9066],

  'SD' => [44.2853,-99.4632],

  'TN' => [35.7449,-86.7489],

  'TX' => [31.1060,-97.6475],

  'UT' => [40.1135,-111.8535],

  'VA' => [37.7680,-78.2057],

  'VI' => [18.0001,-64.8199],

  'VT' => [44.0407,-72.7093],

  'WA' => [47.3917,-121.5708],

  'WI' => [44.2563,-89.6385],

  'WV' => [38.4680,-80.9696],

  'WY' => [42.7475,-107.2085]

}