This ruby code print the names of all people residing in locations within 100 Km (For testing change 100 at line 111 to 10000 as faker gem generates random coordinates which has distance much greater than 100km )

close_friends.rb

require 'rubygems'
require 'json'
require 'pp'
require 'faker'

class Close	
	attr_accessor :id, :name
	@@array = Array.new
	
	def self.all_instances
    	@@array;
  	end
	
	def initialize(id,name)
		 
		 @id = id;
		 @name = name;

		 @@array << self
	end

	def self.printAll()
		for i in 0...@@array.length
			print "ID: ",@@array[i].id ," Name: ", @@array[i].name;
			puts;
		end
	end

	def self.sorting()
	 arr_size = @@array.length
	  loop do
		    swapped = false

		    (arr_size-1).times do |i|
			     if @@array[i].id > @@array[i+1].id
			       	@@array[i].id, @@array[i+1].id = @@array[i+1].id, @@array[i].id
			       	@@array[i].name, @@array[i+1].name = @@array[i+1].name, @@array[i].name
			       	swapped = true
			     end
	    	end

	    break if not swapped
	  end

	  return @@array;
	end

		
end

def to_rad angle
    angle/180 * Math::PI
end

def distance_between_points lat1,lat2,lon1,lon2
	 radius = 6371000; 
	 φ1 = to_rad(lat1);
	 φ2 = to_rad(lat2);
	 Δφ = to_rad(lat2-lat1);
	 Δλ = to_rad(lon2-lon1);

	 a = Math.sin(Δφ/2) * Math.sin(Δφ/2) +
	        Math.cos(φ1) * Math.cos(φ2) *
	        Math.sin(Δλ/2) * Math.sin(Δλ/2);
	 c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

	 distance = radius * c;
	 return (distance/1000);
end

def generating_fake_data
	i=0;
	friend = [];

	100.times do
			
			friend[i] = {
			    :lat => Faker::Number.between(-90, 90)*(Faker::Number.decimal(0, 6).to_f) ,
			    :lon => Faker::Number.between(-180, 180)*(Faker::Number.decimal(0, 6).to_f),
			    :name  => Faker::Name.name,
			    :id => Faker::Number.number(4).to_i
			}
		i = i + 1
	end

	tempHash = {"friend" => friend}	

	File.open("temp.json","w") do |f|   
  		f.write(tempHash.to_json)		#Writing JSON for testing purpose
	end
end

def reading_json
	json = File.read('temp.json'); #Reading JSON file for fetching information
	obj = JSON.parse(json);
	return obj;
end


generating_fake_data();
obj = reading_json();
latitude_gyandhan = 28.521134;
longitude_gyandhan = 77.206567;

j=0,count = 0;
friend_list_length = obj["friend"].length()

for j in 0...friend_list_length 

dist = distance_between_points(latitude_gyandhan,obj["friend"][j]["lat"],longitude_gyandhan,obj["friend"][j]["lon"])	
	if( dist <= 100) #For testing with gyandhan location coordinates ,consider changing 100 to 10000 or greater as faker gem generates random coordinates which has distance much greater than 100km 
			Close.new(obj["friend"][j]["id"],obj["friend"][j]["name"])
			count = count + 1;
	end
end

if count === 0
	puts "For testing with gyandhan location coordinates ,consider changing 100 to 10000 or greater as faker gem generates random coordinates which has distance much greater than 100km";
end

Close.sorting();
Close.printAll();