lib/games_dice/probabilities.rb in games_dice-0.3.3 vs lib/games_dice/probabilities.rb in games_dice-0.3.5

@@ -24,11 +24,11 @@
   # @param [Array<Float>] probs Each entry in the array is the probability of getting a result
   # @param [Integer] offset The result associated with index of 0 in the array
   # @return [GamesDice::Probabilities]
   def initialize( probs = [1.0], offset = 0 )
     # This should *probably* be validated in future, but that would impact performance
-    @probs = probs
+    @probs = check_probs_array probs.clone
     @offset = offset
   end
 
   # @!visibility private
   # the Array, Offset representation of probabilities.
@@ -216,10 +216,17 @@
       end
     end
     GamesDice::Probabilities.new( new_probs, combined_min )
   end
 
+  # Returns a symbol for the language name that this class is implemented in. The C version of the
+  # code is noticeably faster when dealing with larger numbers of possible results.
+  # @return [Symbol] Either :c or :ruby
+  def self.implemented_in
+    :ruby
+  end
+
   # Adds a distribution to itself repeatedly, to simulate a number of dice
   # results being summed.
   # @param [Integer] n Number of repetitions, must be at least 1
   # @return [GamesDice::Probabilities] new distribution
   def repeat_sum n
@@ -283,9 +290,23 @@
     end
     GamesDice::Probabilities.new( new_probs, new_offset )
   end
 
   private
+
+  def check_probs_array probs_array
+    probs_array.map!{ |n| Float(n) }
+    total = probs_array.inject(0.0) do |t,x|
+      if x < 0.0 || x > 1.0
+        raise ArgumentError, "Found probability value #{x} which is not in range 0.0..1.0"
+      end
+      t+x
+    end
+    if (total-1.0).abs > 1e-6
+      raise ArgumentError, "Total probabilities too far from 1.0 for a valid distribution"
+    end
+    probs_array
+  end
 
   def calc_keep_distributions k, q, kmode
     if kmode == :keep_best
       keep_distributions = [ GamesDice::Probabilities.new( [1.0], q * k ) ]
       if p_gt(q) > 0.0 && k > 1