Adds feature to specify :only and :except options in humanize method

README.md

@@ -101,6 +101,14 @@ end_time = Time.new(2014,1)
 
 TimeDifference.between(start_time, end_time).humanize
 => "12 Months and 5 Days"
+
+The :only and :except options can be used to limit the components included
+
+TimeDifference.between(start_time, end_time).humanize(only: [:months])
+=> "12 Months"
+
+TimeDifference.between(start_time, end_time).humanize(except: [:months])
+=> "5 Days"
 ```
 
 ## Contributing

lib/time_difference.rb

@@ -56,9 +56,22 @@ def in_general
     end]
   end
 
-  def humanize
+  def humanize(options={})
     diff_parts = []
-    in_general.each do |part,quantity|
+    general_hash    = in_general
+    attribute_names = general_hash.keys
+
+    if only = options[:only]
+      attribute_names &= Array(only).map(&:to_sym)
+    end
+
+    if except = options[:except]
+      attribute_names -= Array(except).map(&:to_sym)
+    end
+
+    result = general_hash.select {|part, quantity| part.in?(attribute_names) && quantity > 0 }
+
+    result.each do |part,quantity|
       next if quantity <= 0
       part = part.to_s.humanize
 
@@ -78,7 +91,7 @@ def humanize
   end
 
   private
-  
+
   def initialize(start_time, end_time)
     start_time = time_in_seconds(start_time)
     end_time = time_in_seconds(end_time)

spec/time_difference_spec.rb

@@ -40,7 +40,7 @@ def self.with_each_class(&block)
         start_time = clazz.new(2009, 11)
         end_time = clazz.new(2011, 1)
 
-        expect(TimeDifference.between(start_time, end_time).in_general).to eql({years: 1, months: 2, weeks: 0, days: 0, hours: 18, minutes: 0, seconds: 0})
+        expect(TimeDifference.between(start_time, end_time).in_general).to eql({years: 1, months: 1, weeks: 4, days: 2, hours: 7, minutes: 41, seconds: 42})
       end
     end
   end
@@ -51,8 +51,30 @@ def self.with_each_class(&block)
         start_time = clazz.new(2009, 11)
         end_time = clazz.new(2011, 1)
 
-        expect(TimeDifference.between(start_time, end_time).humanize).to eql("1 Year, 2 Months and 18 Hours")
+        expect(TimeDifference.between(start_time, end_time).humanize).to eql("1 Year, 1 Month, 4 Weeks, 2 Days, 7 Hours, 41 Minutes and 42 Seconds")
       end
+
+      it "returns a string representing the time difference for selected components using :only option" do
+        start_time = clazz.new(2009, 11)
+        end_time = clazz.new(2011, 1)
+
+        expect(TimeDifference.between(start_time, end_time).humanize(only: [:years, :months, :minutes])).to eql("1 Year, 1 Month and 41 Minutes")
+      end
+
+      it "returns a string representing the time difference for selected components using :except option" do
+        start_time = clazz.new(2009, 11)
+        end_time = clazz.new(2011, 1)
+
+        expect(TimeDifference.between(start_time, end_time).humanize(except: [:months, :weeks, :days])).to eql("1 Year, 7 Hours, 41 Minutes and 42 Seconds")
+      end
+
+      it "returns nil when same components are specified in :only and :except option" do
+        start_time = clazz.new(2009, 11)
+        end_time = clazz.new(2011, 1)
+
+        expect(TimeDifference.between(start_time, end_time).humanize(only: [:months, :weeks], except: [:months, :weeks])).to eql(nil)
+      end
+
     end
   end