Ruby script to get NorthSouthEastWest ends from shapefile.

geo_ruby_nsew.rb

#! /usr/local/bin/ruby
# coding: utf-8
#*********************************************
# Ruby script to get NorthSouthEastWest ends from shapefile.
#*********************************************
#
require 'georuby'
require 'geo_ruby/shp'

include GeoRuby::Shp4r

class Shp
  def initialize
    @shpfile = "/path/to/shapefile.shp"
  end

  def exec
    # 北・南・東・西の緯度・経度初期値
    n_end, s_end, e_end, w_end = [0, 0], [0, 90], [0, 0], [180, 0]

    begin
      # 東西南北端取得
      ShpFile.open(@shpfile) do |shp|
        shp.each do |s|
          crds = s.geometry.as_json[:coordinates]
          crds.each do |c_0|
            c_0.each do |c_1|
              c_1.each do |c|
                e_end = c if c[0] > e_end[0]
                w_end = c if c[0] < w_end[0]
                n_end = c if c[1] > n_end[1]
                s_end = c if c[1] < s_end[1]
              end
            end
          end
        end
      end

      # 結果出力
      printf("North end: %8.4f%s, %7.4f%s\n", n_end[0], n_end[1])
      printf("South end: %8.4f%s, %7.4f%s\n", s_end[0], s_end[1])
      printf("East  end: %8.4f%s, %7.4f%s\n", e_end[0], e_end[1])
      printf("West  end: %8.4f%s, %7.4f%s\n", w_end[0], w_end[1])
    rescue => e
      $stderr.puts "[ERROR][#{self.class.name}.#{__method__}] #{e}"
      e.backtrace.each{ |trace| $stderr.puts "\t#{trace}" }
      exit 1
    end
  end
end

Shp.new.exec