From f9c53472a05158960217d0e965ed332437643254 Mon Sep 17 00:00:00 2001
From: torshimizu <torshimizu@gmail.com>
Date: Sat, 10 Feb 2018 22:42:52 -0800
Subject: [PATCH 1/4] Created solar_system.rb

to backup file
---
 solar_system.rb | 135 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 solar_system.rb

diff --git a/solar_system.rb b/solar_system.rb
new file mode 100644
index 00000000..6002a8bb
--- /dev/null
+++ b/solar_system.rb
@@ -0,0 +1,135 @@
+require_relative 'classes_methods.rb'
+
+# ______ milky_system ______
+planetA = Planet.new("Mercury")
+planetA.distance_from_sun = 36_000_000
+planetA.year_length = "0.2 Earth years"
+
+planetB = Planet.new("Venus")
+planetB.distance_from_sun = 67_000_000
+planetB.year_length = "0.6 Earth years"
+
+planetC = Planet.new("Earth")
+planetC.distance_from_sun = 93_000_000
+planetC.year_length = "365.26 Earth days"
+
+planetD = Planet.new("Mars")
+planetD.distance_from_sun = 142_000_000
+planetD.year_length = "1.9 Earth years"
+
+planetE = Planet.new("Jupiter")
+planetE.distance_from_sun = 484_000_000
+planetE.year_length = "11.9 Earth years"
+
+planetF = Planet.new("Saturn")
+planetF.distance_from_sun = 887_000_000
+planetF.year_length = "29.5 Earth years"
+
+planetG = Planet.new("Uranus")
+planetG.distance_from_sun = 1_784_000_000
+planetG.year_length = "84 Earth years"
+
+planetH = Planet.new("Neptune")
+planetH.distance_from_sun = 2_794_000_000
+planetH.year_length = "164.8 Earth years"
+
+#____alpha_centauri_____
+planet1 = Planet.new("Alpha Centauri Bb")
+planet1.distance_from_sun = 111_111_111
+planet1.year_length = "123 Earth years"
+
+#____instantiate Solar Systems
+human_system = [planetA, planetB, planetC, planetD, planetE, planetF, planetG, planetH]
+milky_system = SolarSystem.new(human_system, "Milky Way") # making a new human_system
+alpha_planets= [planet1]
+alpha_centauri = SolarSystem.new(alpha_planets, "Alpha Centauri")
+
+menu = [milky_system, alpha_centauri]
+
+#_____for the user interface_____
+puts "Welcome to our Solar System viewer. Let's takeoff . . ."
+puts
+puts "        /\\"
+puts "       |  |"
+puts "       |  |"
+puts "      /|/\\|\\"
+puts "     /_||||_\\"
+puts "      T    T"
+puts "\n"
+
+puts "MENU:"
+puts "0: Add a planet"
+print_menu(menu)
+print "Please select the number of the menu item to access: "
+menu_selection = gets.chomp.to_i
+puts
+
+case menu_selection
+when 0
+  print "Would you like to create a new planet? > "
+  create_new = gets.chomp.downcase
+  puts
+  case create_new
+  when "yes", "y"
+    users_solar_system = get_solar_system(menu) # getting solar system to add to
+    puts
+
+    new_planet_name = get_planet_name # getting users planet name
+    user_planet = Planet.new(new_planet_name) # instantiating a new planet
+    users_solar_system.add_new_planet(user_planet) # adding the new planet to the human_system hash
+    puts
+
+    new_planet_dist = get_distance # getting the distance of the newly created planet
+    user_planet.distance_from_sun = new_planet_dist # adding this new distance to the planet's instance
+    puts
+
+    new_planet_year = get_year
+    user_planet.year_length = new_planet_year
+    puts
+  else # THIS CURRENTLY DOES NOT LOOP BACK INTO A MENU THAT CAN BE INTERACTED WITH
+    puts "I wouldn't want to play god either! \n \n"
+    puts "MENU:"
+    puts "0: Add a planet"
+    print_menu(menu)
+    print "Please select the number of the system you would like to browse: "
+    menu_selection = gets.chomp.to_i
+  end
+when 1, 2
+  working_system = choose_system(menu, menu_selection)
+
+  puts "\n"
+
+  view_systems = true
+  until view_systems == false
+
+
+    print_planet_menu = true
+    until print_planet_menu == false
+      puts "Here is the list of planets in the #{working_system.sys_name}:"
+      puts
+      choose_planet(working_system)
+      planet_choice = gets.chomp.to_i
+      puts
+
+      until working_system.planet_hash.keys.include?(planet_choice)
+        puts "Invalid selection. Please choose a planet from the following list: "
+        choose_planet(working_system)
+        planet_choice = gets.chomp.to_i
+      end
+      puts working_system.planet_hash[planet_choice].planet_summary
+      puts
+
+      print "Would you like to see information on another planet? > "
+      loop_again = gets.chomp.downcase
+      print_planet_menu = keep_looping(loop_again)
+      puts
+    end
+
+    print "Would you like to view another system? > "
+    loop_all_again = gets.chomp.downcase
+    view_systems = keep_looping(loop_all_again)
+  end
+
+  puts
+  puts "Reentering atmosphere. See ya, Earthling~"
+end

From cda7c42bca919cc12eaf6336431996212fe5d324 Mon Sep 17 00:00:00 2001
From: torshimizu <torshimizu@gmail.com>
Date: Sat, 10 Feb 2018 22:43:54 -0800
Subject: [PATCH 2/4] Create solar_classes_methods.rb

Uploading to backup file
---
 solar_classes_methods.rb | 162 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 solar_classes_methods.rb

diff --git a/solar_classes_methods.rb b/solar_classes_methods.rb
new file mode 100644
index 00000000..c1079a79
--- /dev/null
+++ b/solar_classes_methods.rb
@@ -0,0 +1,162 @@
+class Planet
+  attr_reader :name
+  attr_accessor :year_length, :distance_from_sun
+
+  def initialize(planet_name)
+    @name = planet_name
+  end
+
+  def planet_summary
+    return "#{name}: \n Takes #{year_length} to orbit the sun. \n It's distance from the sun is #{distance_from_sun} miles."
+  end
+end
+
+class SolarSystem
+  attr_reader :planets, :sys_name # evaluate if this was a good choice for planets
+  # attr_accessor :planets
+
+  def initialize(planets, sys_name)
+    @planets = planets
+    @sys_name = sys_name
+    @all_summary = Array.new
+    @planet_names = Array.new
+    @planet_hash = Hash.new
+    create_planet_hash
+    planet_names
+
+  end
+
+  def add_new_planet(new_planet)
+    @planets << new_planet
+    create_planet_hash
+    create_all_summary
+  end
+
+  def create_planet_hash # this method ties the index +1 of the planet to the instance of the planet, for selection in the menu
+    # @planet_hash = Hash[@planet_names.zip(@planets)]
+    @planets.each.with_index(1) do |planet, index|
+      @planet_hash[index] = planet
+    end
+  end
+
+  def planet_hash
+    @planet_hash
+  end
+
+  def planet_names # creates an array of planet_names maybe this should just be built in to create_planet_hash - same info can be accessed from there.
+    @planets.each do |planet|
+      @planet_names << planet.name
+    end
+  end
+
+  # def list_planet_names
+  #   @planet_names
+  # end
+
+  def listplanets
+    numbered_planets = []
+    @planets.each.with_index(1) do |planet, index|
+      numbered_planet = "#{index}: #{planet.name}"
+      numbered_planets << numbered_planet
+    end
+    numbered_planets = numbered_planets.join("\n")
+    return numbered_planets
+  end
+
+  # ______ these methods are not used in UI ______
+  def create_all_summary
+    @planets.each { |planet| @all_summary << planet.planet_summary }
+  end
+
+  def print_all_summary
+    @all_summary
+  end
+
+end
+
+
+# ________ methods when adding a new planet _________
+
+def get_solar_system(menu)
+  puts "Which solar system is the planet in? "
+  print_menu(menu)
+  print "> "
+  users_system = gets.chomp.to_i
+  if users_system == 1
+    users_system = menu[0]
+  elsif users_system == 2
+    users_system = menu[1]
+  else
+    puts "WARNING: I don't know that system."
+  end
+  return users_system
+end
+
+def get_planet_name
+  print "What is the name your new planet? > "
+  new_planet_name = gets.chomp.capitalize
+  return new_planet_name
+end
+
+def get_distance # might need to convert ',' to '_' for bignums
+  print "How far is this planet from the Sun in miles? > "
+  miles_from_sun = gets.chomp.to_i
+end
+
+def get_year
+  print "How many Earth years does it take to orbit the Sun? > "
+  planet_year = gets.chomp.to_f
+end
+
+# _________ methods for user interface _________
+
+def print_menu(menu)
+  menu.each.with_index(1) do |sol_sys, listno|
+    puts "#{listno}: #{sol_sys.sys_name}"
+  end
+  puts
+end
+
+def choose_system(menu, chosen_system) # I'm not sure why I made this a method
+  if chosen_system == 1 # this works for now, but is not futureproof (a system cannot be added)
+    working_system = menu[0]
+    return working_system
+  elsif chosen_system == 2
+    working_system = menu[1]
+    return working_system
+  else
+    puts "I don't know that system!"
+  end
+  loop_menu = true
+  unless loop_menu == false
+    print "Would you like to see a different system? (yes/no) > "
+    loop_menu = gets.chomp.downcase
+    case loop_menu
+    when "yes", "y"
+      print_menu(menu)
+      working_system = choose_system(menu) # this is called recursion(?)
+    when "no", "n"
+      loop_menu = false
+      puts
+      puts "Reentering atmosphere. See ya, Earthling~"
+      exit
+    end
+  end
+end
+
+def choose_planet(working_system)
+  puts working_system.listplanets
+  puts
+  print "Please select the number of the planet you want to see: "
+end
+
+def keep_looping(input_variable)
+  case input_variable
+  when "yes", "y"
+    return true
+  when "no", "n"
+    return false
+  else
+    puts "I'm not sure what you want"
+  end
+end

From 65a42bd152c3013b3769c7ee2c092221ee02fc2a Mon Sep 17 00:00:00 2001
From: torshimizu <torshimizu@gmail.com>
Date: Sun, 11 Feb 2018 23:03:56 -0800
Subject: [PATCH 3/4] Update solar_system.rb

---
 solar_system.rb | 253 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 172 insertions(+), 81 deletions(-)

diff --git a/solar_system.rb b/solar_system.rb
index 6002a8bb..4615d924 100644
--- a/solar_system.rb
+++ b/solar_system.rb
@@ -2,49 +2,63 @@
 
 # ______ milky_system ______
 planetA = Planet.new("Mercury")
-planetA.distance_from_sun = 36_000_000
-planetA.year_length = "0.2 Earth years"
+planetA.distance_from_sun = 57_900_000
+planetA.year_length = 0.2
+planetA.diameter = 4878
 
 planetB = Planet.new("Venus")
-planetB.distance_from_sun = 67_000_000
-planetB.year_length = "0.6 Earth years"
+planetB.distance_from_sun = 108_160_000
+planetB.year_length = 0.6
+planetB.diameter = 12_104
 
 planetC = Planet.new("Earth")
 planetC.distance_from_sun = 93_000_000
-planetC.year_length = "365.26 Earth days"
+planetC.year_length = 1
+planetC.diameter = 12_756
 
 planetD = Planet.new("Mars")
-planetD.distance_from_sun = 142_000_000
-planetD.year_length = "1.9 Earth years"
+planetD.distance_from_sun = 227_936_640
+planetD.year_length = 1.9
+planetD.diameter = 6794
 
 planetE = Planet.new("Jupiter")
-planetE.distance_from_sun = 484_000_000
-planetE.year_length = "11.9 Earth years"
+planetE.distance_from_sun = 778_369_000
+planetE.year_length = 11.9
+planetE.diameter = 142_984
 
 planetF = Planet.new("Saturn")
-planetF.distance_from_sun = 887_000_000
-planetF.year_length = "29.5 Earth years"
+planetF.distance_from_sun = 1_427_034_000
+planetF.year_length = 29.5
+planetF.diameter = 120_536
 
 planetG = Planet.new("Uranus")
-planetG.distance_from_sun = 1_784_000_000
-planetG.year_length = "84 Earth years"
+planetG.distance_from_sun = 2_870_658_186
+planetG.year_length = "84"
+planetG.diameter = 51_118
 
 planetH = Planet.new("Neptune")
-planetH.distance_from_sun = 2_794_000_000
-planetH.year_length = "164.8 Earth years"
+planetH.distance_from_sun = 4_496_976_000
+planetH.year_length = "164.8"
+planetH.diameter = 49_532
 
 #____alpha_centauri_____
-planet1 = Planet.new("Alpha Centauri Bb")
-planet1.distance_from_sun = 111_111_111
-planet1.year_length = "123 Earth years"
+planet1 = Planet.new("Alpha Centauri Bc")
+planet1.distance_from_sun = 21_093_000
+planet1.year_length = 12
+planet1.diameter = 12_000
+
+planet2 = Planet.new("Proxima Centauri b")
+planet2.distance_from_sun = 7_500_000
+planet2.year_length = 11.2
+planet2.diameter = 14_030
 
 #____instantiate Solar Systems
 human_system = [planetA, planetB, planetC, planetD, planetE, planetF, planetG, planetH]
 milky_system = SolarSystem.new(human_system, "Milky Way") # making a new human_system
-alpha_planets= [planet1]
+alpha_planets= [planet1, planet2]
 alpha_centauri = SolarSystem.new(alpha_planets, "Alpha Centauri")
 
-menu = [milky_system, alpha_centauri]
+menu = [milky_system, alpha_centauri] # this has now become a poor variable name
 
 #_____for the user interface_____
 puts "Welcome to our Solar System viewer. Let's takeoff . . ."
@@ -57,79 +71,156 @@
 puts "      T    T"
 puts "\n"
 
-puts "MENU:"
-puts "0: Add a planet"
-print_menu(menu)
-print "Please select the number of the menu item to access: "
-menu_selection = gets.chomp.to_i
-puts
+menu_viewer = true
+until menu_viewer == false
 
-case menu_selection
-when 0
-  print "Would you like to create a new planet? > "
-  create_new = gets.chomp.downcase
+
+  puts "\nMENU:"
+  puts "0: Other options"
+  print_menu(menu)
+  print "Please select the number of the menu item to access: "
+  menu_selection = gets.chomp.to_i
   puts
-  case create_new
-  when "yes", "y"
-    users_solar_system = get_solar_system(menu) # getting solar system to add to
-    puts
-
-    new_planet_name = get_planet_name # getting users planet name
-    user_planet = Planet.new(new_planet_name) # instantiating a new planet
-    users_solar_system.add_new_planet(user_planet) # adding the new planet to the human_system hash
-    puts
-
-    new_planet_dist = get_distance # getting the distance of the newly created planet
-    user_planet.distance_from_sun = new_planet_dist # adding this new distance to the planet's instance
-    puts
-
-    new_planet_year = get_year
-    user_planet.year_length = new_planet_year
-    puts
-  else # THIS CURRENTLY DOES NOT LOOP BACK INTO A MENU THAT CAN BE INTERACTED WITH
-    puts "I wouldn't want to play god either! \n \n"
-    puts "MENU:"
-    puts "0: Add a planet"
-    print_menu(menu)
-    print "Please select the number of the system you would like to browse: "
-    menu_selection = gets.chomp.to_i
-  end
-when 1, 2
-  working_system = choose_system(menu, menu_selection)
 
-  puts "\n"
+  #_______ this needs case/when statement for selecting between adding a planet and calculating the distance between two planets in one system
 
-  view_systems = true
-  until view_systems == false
+  case menu_selection
+  when 0
+    other_options = {1 => "Add a planet", 2 => "Calculate distance between two planets"}
+    print_other_options(other_options)
+    print "\nPlease select the number of the menu item to access: "
+    select_other_option = gets.chomp.to_i
 
+    until other_options.keys.include?(select_other_option)
+      puts "Invalid selection. Please select a number from the following menu: "
+      print_other_options(other_options)
+      select_other_option = gets.chomp.to_i
+    end
 
-    print_planet_menu = true
-    until print_planet_menu == false
-      puts "Here is the list of planets in the #{working_system.sys_name}:"
-      puts
-      choose_planet(working_system)
-      planet_choice = gets.chomp.to_i
+    case select_other_option
+    when 1
+      print "Would you like to create a new planet? > "
+      create_new = gets.chomp.downcase
       puts
 
-      until working_system.planet_hash.keys.include?(planet_choice)
-        puts "Invalid selection. Please choose a planet from the following list: "
-        choose_planet(working_system)
-        planet_choice = gets.chomp.to_i
+      unless create_new == ("no" || "n")
+        puts "Which solar system is the planet in? "
+        users_solar_system = get_solar_system(menu) # getting solar system to add to
+        puts
+
+        new_planet_name = get_planet_name # getting users planet name
+        user_planet = Planet.new(new_planet_name) # instantiating a new planet
+        users_solar_system.add_new_planet(user_planet) # adding the new planet to the human_system hash
+        puts
+
+        new_planet_dist = get_distance # getting the distance of the newly created planet
+        user_planet.distance_from_sun = new_planet_dist # adding this new distance to the planet's instance
+        puts
+
+        new_planet_year = get_year
+        user_planet.year_length = new_planet_year
+        puts
+
+        puts user_planet.planet_summary
+        puts
+      else
+        puts "I wouldn't want to play god either! \n \n"
       end
-      puts working_system.planet_hash[planet_choice].planet_summary
-      puts
 
-      print "Would you like to see information on another planet? > "
-      loop_again = gets.chomp.downcase
-      print_planet_menu = keep_looping(loop_again)
-      puts
+    when 2
+      print "\nWould you like to calculate the distance between two planets in the same system? > "
+      calculate_distance = gets.chomp.downcase
+
+
+      unless calculate_distance == ("no" || "n")
+        puts "\nWhich solar system are the planets in?"
+        users_solar_system = get_solar_system(menu)
+        puts
+        # working_system = choose_system(menu, users_solar_system)
+
+        # print_planet_menu = true
+        # until print_planet_menu == false
+        puts "Here is the list of planets in the #{users_solar_system.sys_name}:"
+        puts
+        puts users_solar_system.listplanets
+        print "Please select the number of the first planet: "
+        planet_choice1 = gets.chomp.to_i
+        puts
+
+        until users_solar_system.planet_hash.keys.include?(planet_choice1)
+          puts "Invalid selection. Please choose a planet from the following list: "
+          puts users_solar_system.listplanets
+          puts "> "
+          planet_choice1 = gets.chomp.to_i
+        end
+
+        print "Please select the number of the second planet: "
+        planet_choice2 = gets.chomp.to_i
+
+        until users_solar_system.planet_hash.keys.include?(planet_choice2) # this isn't DRY
+          puts "Invalid selection. Please choose a planet from the following list: "
+          puts users_solar_system.listplanets
+          planet_choice2 = gets.chomp.to_i
+          puts "> "
+        end
+      end
+
+      #____ need to correlate numbered choice to planet
+      planet_choice1 = users_solar_system.planet_hash[planet_choice1]
+      planet_choice2 = users_solar_system.planet_hash[planet_choice2]
+      distance_between_planets = planet_choice1.distance_from_sun - planet_choice2.distance_from_sun
+      puts "#{planet_choice1.name} is #{distance_between_planets} km away from #{planet_choice2.name}."
     end
 
-    print "Would you like to view another system? > "
-    loop_all_again = gets.chomp.downcase
-    view_systems = keep_looping(loop_all_again)
+  when 1, 2
+    working_system = choose_system(menu, menu_selection)
+
+    puts "\n"
+
+    # view_systems = true
+    # until view_systems == false
+
+
+      print_planet_menu = true
+      until print_planet_menu == false
+        puts "Here is the list of planets in the #{working_system.sys_name}:"
+        puts
+        choose_planet(working_system)
+        planet_choice = gets.chomp.to_i
+        puts
+
+        until working_system.planet_hash.keys.include?(planet_choice) || planet_choice == 0
+          puts "Invalid selection. Please choose a planet from the following list: "
+          choose_planet(working_system)
+          planet_choice = gets.chomp.to_i
+        end
+
+        case planet_choice
+        when 0
+          puts working_system.print_all_summary
+        else
+          puts working_system.planet_hash[planet_choice].planet_summary
+        end
+        puts
+
+        print "Would you like to see information on another planet in this system? > "
+        loop_again = gets.chomp.downcase
+        print_planet_menu = keep_looping(loop_again)
+        # puts
+      end
+      print "\nWould you like to view the menu? > "
+      viewing_menu = gets.chomp.downcase
+      menu_viewer = keep_looping(viewing_menu)
+
+      # print "Would you like to view another system? > "
+      # loop_all_again = gets.chomp.downcase
+      # view_systems = keep_looping(loop_all_again)
+    # end
+  else
+    puts "Invalid selection. \n Please select a number from the following menu: "
+    next
   end
 
-  puts
-  puts "Reentering atmosphere. See ya, Earthling~"
 end
+puts
+puts "Reentering atmosphere. See ya, Earthling~"

From fc9c2c0e70e260fa9ac46a148d512b9a0179ee32 Mon Sep 17 00:00:00 2001
From: torshimizu <torshimizu@gmail.com>
Date: Sun, 11 Feb 2018 23:04:30 -0800
Subject: [PATCH 4/4] Update solar_classes_methods.rb

---
 solar_classes_methods.rb | 71 +++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 27 deletions(-)

diff --git a/solar_classes_methods.rb b/solar_classes_methods.rb
index c1079a79..79fcc187 100644
--- a/solar_classes_methods.rb
+++ b/solar_classes_methods.rb
@@ -1,13 +1,13 @@
 class Planet
   attr_reader :name
-  attr_accessor :year_length, :distance_from_sun
+  attr_accessor :year_length, :distance_from_sun, :diameter
 
   def initialize(planet_name)
     @name = planet_name
   end
 
   def planet_summary
-    return "#{name}: \n Takes #{year_length} to orbit the sun. \n It's distance from the sun is #{distance_from_sun} miles."
+    return "#{name}: \n Takes #{year_length} Earth years to orbit the sun. \n It's distance from the sun is #{distance_from_sun} km. \n #{name}\'s diameter is #{diameter} km."
   end
 end
 
@@ -21,6 +21,7 @@ def initialize(planets, sys_name)
     @all_summary = Array.new
     @planet_names = Array.new
     @planet_hash = Hash.new
+    create_all_summary
     create_planet_hash
     planet_names
 
@@ -49,12 +50,8 @@ def planet_names # creates an array of planet_names maybe this should just be bu
     end
   end
 
-  # def list_planet_names
-  #   @planet_names
-  # end
-
   def listplanets
-    numbered_planets = []
+    numbered_planets = ["0: List all summaries"]
     @planets.each.with_index(1) do |planet, index|
       numbered_planet = "#{index}: #{planet.name}"
       numbered_planets << numbered_planet
@@ -63,7 +60,7 @@ def listplanets
     return numbered_planets
   end
 
-  # ______ these methods are not used in UI ______
+# ________ the following methods can be produced by looping over @planets and printing each planet's summary
   def create_all_summary
     @planets.each { |planet| @all_summary << planet.planet_summary }
   end
@@ -75,22 +72,8 @@ def print_all_summary
 end
 
 
-# ________ methods when adding a new planet _________
+# ________ methods for other options _________
 
-def get_solar_system(menu)
-  puts "Which solar system is the planet in? "
-  print_menu(menu)
-  print "> "
-  users_system = gets.chomp.to_i
-  if users_system == 1
-    users_system = menu[0]
-  elsif users_system == 2
-    users_system = menu[1]
-  else
-    puts "WARNING: I don't know that system."
-  end
-  return users_system
-end
 
 def get_planet_name
   print "What is the name your new planet? > "
@@ -100,12 +83,28 @@ def get_planet_name
 
 def get_distance # might need to convert ',' to '_' for bignums
   print "How far is this planet from the Sun in miles? > "
-  miles_from_sun = gets.chomp.to_i
+  miles_from_sun = gets.chomp
+  miles_from_sun = match_number(miles_from_sun)
 end
 
 def get_year
   print "How many Earth years does it take to orbit the Sun? > "
-  planet_year = gets.chomp.to_f
+  planet_year = gets.chomp
+  miles_from_sun = match_number(planet_year)
+end
+
+def match_number(num)
+  until num.match(/^\-?\d*\.?\d*$/) && !num.empty?
+    if !num.match(/^\-?\d*\.?\d*$/)
+      print "Invalid input. Please enter a number without commas: "
+      num = gets.chomp
+    end
+    if num.empty?
+      print "No number inputted. Please enter a number: "
+      num = gets.chomp
+    end
+  end
+  return num
 end
 
 # _________ methods for user interface _________
@@ -117,6 +116,20 @@ def print_menu(menu)
   puts
 end
 
+def get_solar_system(menu) # not sure why I have both this method and choose_system
+  print_menu(menu)
+  print "> "
+  users_system = gets.chomp.to_i
+  if users_system == 1
+    users_system = menu[0]
+  elsif users_system == 2
+    users_system = menu[1]
+  else
+    puts "WARNING: I don't know that system."
+  end
+  return users_system
+end
+
 def choose_system(menu, chosen_system) # I'm not sure why I made this a method
   if chosen_system == 1 # this works for now, but is not futureproof (a system cannot be added)
     working_system = menu[0]
@@ -134,7 +147,7 @@ def choose_system(menu, chosen_system) # I'm not sure why I made this a method
     case loop_menu
     when "yes", "y"
       print_menu(menu)
-      working_system = choose_system(menu) # this is called recursion(?)
+      working_system = choose_system(menu, chosen_system) # this is called recursion(?)
     when "no", "n"
       loop_menu = false
       puts
@@ -147,7 +160,11 @@ def choose_system(menu, chosen_system) # I'm not sure why I made this a method
 def choose_planet(working_system)
   puts working_system.listplanets
   puts
-  print "Please select the number of the planet you want to see: "
+  print "Please select the number of the item you would like to see: "
+end
+
+def print_other_options(other_options)
+  other_options.each { |num, option| puts "#{num}: #{option}" }
 end
 
 def keep_looping(input_variable)