refactoring extra/missing box error

features/cleanup_distance.feature

@@ -20,12 +20,6 @@ Feature: Cleanup distance
     When I calculate the cleanup distance for box 2 of stack 1
     Then the score for that box should be 2
 
-  Scenario: +100 if target box is totally missing
-    Given the target is [[:r]]
-    And the observed is [[]]
-    When I calculate the cleanup distance for box 1 of stack 1
-    Then the score for that box should be 100
-
   Scenario: count boxes moved when retrieving replacement
     Given the target is [[:r], [:b,:b]]
     And the observed is [[],[:r,:b,:b]]
@@ -135,6 +129,18 @@ Feature: Cleanup distance
     When I calculate the cleanup distance
     Then the score should be 37
 
+  Scenario: the presence of extra boxes should be penalized
+    Given the target is [[]]
+    And the observed is [[:r, :r]]
+    When I calculate the cleanup distance
+    Then the score should be 203
+
+  Scenario: the lack of needed boxes should be penalized
+    Given the target is [[:r, :r]]
+    And the observed is [[]]
+    When I calculate the cleanup distance
+    Then the score should be 200
+
 
   Scenario: it should provide a numeric answer for arbitrary rearrangements
     Given I have 100 arbitrary target:objective pairs with 5 stacks and 5 crates each

lib/cargobot.rb

@@ -187,7 +187,7 @@ def crate_cleanup_error(target, stack_number, box_number)
       return 0 
     else
       possible_replacements = topmost_matches(expected_box)
-      return 100 if possible_replacements.empty?
+      return 0 if possible_replacements.empty?
 
       this_stack_replacement = @stacks[stack].rindex(expected_box).nil? ?
         nil :
@@ -226,11 +226,16 @@ def stack_cleanup_error(target, stack_number)
 
 
   def cleanup_error(target)
-    target.stacks.each_with_index.inject(0) do |sum,(stack,idx)|
+    stack_error = target.stacks.each_with_index.inject(0) do |sum,(stack,idx)|
       sum + stack_cleanup_error(target,idx+1)
     end
+
+    extra_boxes_error = (target.stacks.flatten.length - @stacks.flatten.length).abs*100
+
+    stack_error + extra_boxes_error
   end
 
+
   def topmost_matches(crate)
     @stacks.collect {|s| (s.length - s.rindex(crate)) unless s.rindex(crate).nil?}.compact
   end