Module: Geo3x3

Defined in:
lib/geo3x3.rb,
lib/geo3x3/version.rb

Constant Summary collapse

VERSION = 
"0.0.4"

Class Method Summary collapse

Class Method Details

.decode(code) ⇒ Object 



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# File 'lib/geo3x3.rb', line 72

def self.decode(code)
  code =
    case code
    when Integer
      code.west_longitude? ? "W#{code}" : "E#{code}"
    when String
      raise ArgumentError if code.empty?
      code
    else
      raise ArgumentError
    end

  unit = 180.0
  lat = 0.0
  lng = 0.0
  level = 1

  code[1..-1].each_char do |c|
    break if c == "0"
    n = c.to_i

    unit /= 3
    n -= 1
    lng += (n % 3) * unit
    lat += (n / 3) * unit
    level += 1
  end

  lat += unit / 2
  lng += unit / 2
  lat = 90 - lat
  lng -= 180 if code.west_longitude?

  {
    lat:   lat,
    lng:   lng,
    level: level,
    unit:  unit
  }
end

.encode(*params) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/geo3x3.rb', line 34

def self.encode(*params)
  if params.size == 3 && params.all? {|i| i.kind_of? Numeric}
    lat, lng, level = *params
    lat = lat.to_f
    lng = lng.to_f
  elsif params[0].kind_of? Hash
    lat = params[0][:lat].to_f
    lng = params[0][:lng].to_f
    level = params[0][:level]
  else
    raise ArgumentError
  end
  raise ArgumentError if level < 1

  code = 
    if lng.east_longitude?
      "E"
    else
      lng += 180
      "W"
    end

  lat = 90 - lat

  unit = 180.0 
  (level-1).times do
    unit /= 3
    x = (lng/unit).floor
    y = (lat/unit).floor
    code += ((x + y*3) + 1).to_s

    lng -= x * unit
    lat -= y * unit
  end

  code
end