Module: Piggly::Util::Enumerable

Defined in:
lib/piggly/util/enumerable.rb

Class Method Summary collapse

Class Method Details

.count(enum) ⇒ Object

Count number of elements, optionally filtered by a block



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# File 'lib/piggly/util/enumerable.rb', line 6

def self.count(enum)
  if block_given?
    enum.inject(0){|count,e| yield(e) ? count + 1 : count }
  else
    enum.length
  end
end

.group_by(enum, collection = Hash.new{|h,k| h[k] = [] }) ⇒ Object

Collect an elements into disjoint sets, grouped by result of the block



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# File 'lib/piggly/util/enumerable.rb', line 29

def self.group_by(enum, collection = Hash.new{|h,k| h[k] = [] })
  enum.inject(collection) do |hash, item|
    hash[yield(item)] << item
    hash
  end
end

.index_by(enum, collection = Hash.new) ⇒ Object 



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# File 'lib/piggly/util/enumerable.rb', line 36

def self.index_by(enum, collection = Hash.new)
  enum.inject(collection) do |hash, item|
    hash.update(yield(item) => item)
  end
end

.sum(enum, default = 0, &block) ⇒ Object

Compute sum of elements, optionally transformed by a block



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# File 'lib/piggly/util/enumerable.rb', line 15

def self.sum(enum, default = 0, &block)
  enum = enum.to_a
  return default if enum.empty?

  head, *tail = enum

  if block_given?
    tail.inject(yield(head)){|sum,e| sum + yield(e) }
  else
    tail.inject(head){|sum,e| sum + e }
  end
end