lib/easystats.rb in easystats-0.0.2 vs lib/easystats.rb in easystats-0.0.3

@@ -14,30 +14,44 @@
     sum_of_numbers
   end
 
   # take in an array of numbers and calculate the mean (average)
   def mean(data)
-    self.sum(data) / data.count
+    self.sum(data) / data.count.to_f
   end
 
-  # take in an array of numbers and calculate the standard deviation
-  def standard_deviation(data)
-    average = self.mean(data)
+  # this is an internat function (technically the developer can use it but should have no need)
+  # this function returns the sum of each squared difference of mean
+  def sum_of_deviations_squared(data)
     deviations = Array.new
+    average = self.mean(data)
     sum_of_deviations = 0
 
     data.each do |num|
       deviations.push((num-average)**2)
     end
 
     deviations.each do |num|
       sum_of_deviations += num
     end
 
+    sum_of_deviations
+  end
+
+  # take in an array of numbers and calculate the standard deviation
+  def standard_deviation(data)
+    sum_of_deviations = self.sum_of_deviations_squared(data)
+
     Math::sqrt(sum_of_deviations / (data.count-1))
   end
 
+  def variance(data)
+    average = self.mean(data)
+    sum_of_deviations = self.sum_of_deviations_squared(data)
+    sum_of_deviations / data.count.to_f
+  end
+
   # take in the array of numbers and calculate the median
   def median(data)
     halfway = data.count / 2
 
     # Sort the array
@@ -46,11 +60,11 @@
     # The median will be different based on the number of numbers in the array
     # If there is an even number in the array
     if(data.count % 2) == 0
       median = (data[halfway] + data[halfway-1]) / 2.0
 
-    # Else, there is an odd number in the array
+    # Else, there is an odd number of elements in the array
     else
       median = data[halfway]
     end
 
     median
@@ -60,7 +74,66 @@
   def range(data)
     # Sort the array
     data = data.sort
     data[data.count-1] - data[0]
   end
-end
 
+  # take in an array of numbers and return the mode
+  def mode(data)
+    # Sort the array
+    data = data.sort
+
+    # create a flag to tell the user if all the numbers only appear once
+    no_mode = true
+
+    # The variable that will hold the highest number
+    highest_value = 0
+   
+    # The variable that holds the most time the value appears
+    most_times = 0
+
+    # Create a new hash to hold the numbers
+    tmp = Hash.new
+
+    # Populate the hash
+    data.each do |num|
+      if tmp["#{num}"].nil? == false
+        tmp["#{num}"] = tmp["#{num}"].to_i + 1
+      else
+        tmp["#{num}"] = 1
+      end
+    end
+
+    # Check to make sure that there is a mode
+    data.each do |num|
+      if tmp["#{num}"].to_i > 1
+        no_mode = false
+      end
+    end
+ 
+    if no_mode == true
+      "There is no mode"
+    else
+      data.each do |num|
+        if tmp["#{num}"].to_i > most_times
+          highest_value = num
+          most_times = tmp["#{num}"]
+        end 
+      end
+
+      # now loop through again just to make sure another number doesn't appear an equal number of times
+      data.each do |num|
+        if num != highest_value
+          if tmp["#{num}"].to_i == most_times
+            no_mode = true
+          end
+        end
+      end
+ 
+      if no_mode == true
+        "There is no mode"
+      else
+        highest_value
+      end
+    end
+  end
+end