Add in_groups to ActiveSupport::CoreExtensions::Array::Grouping. [#579 state:resolved]

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

1 files changed, 45 insertions, 2 deletions

diff --git a/activesupport/lib/active_support/core_ext/array/grouping.rb b/activesupport/lib/active_support/core_ext/array/grouping.rb
index 767acc4e07..df37afb053 100644
--- a/activesupport/lib/active_support/core_ext/array/grouping.rb
+++ b/activesupport/lib/active_support/core_ext/array/grouping.rb
@@ -4,8 +4,8 @@ module ActiveSupport #:nodoc:
   module CoreExtensions #:nodoc:
     module Array #:nodoc:
       module Grouping
-        # Iterates over the array in groups of size +number+, padding any remaining 
-        # slots with +fill_with+ unless it is +false+.
+        # Splits or iterates over the array in groups of size +number+,
+        # padding any remaining slots with +fill_with+ unless it is +false+.
         # 
         #   %w(1 2 3 4 5 6 7).in_groups_of(3) {|g| p g}
         #   ["1", "2", "3"]
@@ -39,6 +39,49 @@ module ActiveSupport #:nodoc:
           end
         end
 
+        # Splits or iterates over the array in +number+ of groups, padding any
+        # remaining slots with +fill_with+ unless it is +false+.
+        #
+        #   %w(1 2 3 4 5 6 7 8 9 10).in_groups(3) {|g| p g}
+        #   ["1", "2", "3", "4"]
+        #   ["5", "6", "7", nil]
+        #   ["8", "9", "10", nil]
+        #
+        #   %w(1 2 3 4 5 6 7).in_groups(3, ' ') {|g| p g}
+        #   ["1", "2", "3"]
+        #   ["4", "5", " "]
+        #   ["6", "7", " "]
+        #
+        #   %w(1 2 3 4 5 6 7).in_groups(3, false) {|g| p g}
+        #   ["1", "2", "3"]
+        #   ["4", "5"]
+        #   ["6", "7"]
+        def in_groups(number, fill_with = nil)
+          # size / number gives minor group size;
+          # size % number gives how many objects need extra accomodation;
+          # each group hold either division or division + 1 items.
+          division = size / number
+          modulo = size % number
+
+          # create a new array avoiding dup
+          groups = []
+          start = 0
+
+          number.times do |index|
+            length = division + (modulo > 0 && modulo > index ? 1 : 0)
+            padding = fill_with != false &&
+              modulo > 0 && length == division ? 1 : 0
+            groups << slice(start, length).concat([fill_with] * padding)
+            start += length
+          end
+
+          if block_given?
+            groups.each{|g| yield(g) }
+          else
+            groups
+          end
+        end
+
         # Divides the array into one or more subarrays based on a delimiting +value+
         # or the result of an optional block.
         #