Module: Enumerable

Included in:
Archive::Tar::Minitar::Input, Dictionary, Duration, LinkedList, Tuple
Defined in:
lib/more/facets/thread.rb,
lib/more/facets/elementor.rb,
lib/core/facets/conversion.rb,
lib/core/facets/enumerable/each.rb,
lib/core/facets/enumerable/mash.rb,
lib/core/facets/enumerable/count.rb,
lib/core/facets/enumerable/split.rb,
lib/core/facets/enumerable/collect.rb,
lib/core/facets/enumerable/cartesian.rb,
lib/core/facets/enumerable/combination.rb,
lib/core/facets/enumerable/permutation.rb,
lib/core/facets/enumerable/probability.rb

Defined Under Namespace

Classes: Elementor, Enumerator

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.cart ⇒ Object

Provides the cross-product of two or more Enumerables. This is the class-level method. The instance method calls on this.

Enumerable.cart([1,2], [4], ["apple", "banana"])
#=> [[1, 4, "apple"], [1, 4, "banana"], [2, 4, "apple"], [2, 4, "banana"]]

Enumerable.cart([1,2], [3,4])
#=> [[1, 3], [1, 4], [2, 3], [2, 4]]

CREDIT: Thomas Hafner



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# File 'lib/core/facets/enumerable/cartesian.rb', line 34

def self.cartesian_product(*enums, &block)
  result = [[]]
  while [] != enums
    t, result = result, []
    b, *enums = enums
    t.each do |a|
      b.each do |n|
        result << a + [n]
      end
    end
  end
  if block_given?
    result.each{ |e| block.call(e) }
  else
    result
  end
end

.cartesian_product(*enums, &block) ⇒ Object

Provides the cross-product of two or more Enumerables. This is the class-level method. The instance method calls on this.

Enumerable.cart([1,2], [4], ["apple", "banana"])
#=> [[1, 4, "apple"], [1, 4, "banana"], [2, 4, "apple"], [2, 4, "banana"]]

Enumerable.cart([1,2], [3,4])
#=> [[1, 3], [1, 4], [2, 3], [2, 4]]

CREDIT: Thomas Hafner



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# File 'lib/core/facets/enumerable/cartesian.rb', line 15

def self.cartesian_product(*enums, &block)
  result = [[]]
  while [] != enums
    t, result = result, []
    b, *enums = enums
    t.each do |a|
      b.each do |n|
        result << a + [n]
      end
    end
  end
  if block_given?
    result.each{ |e| block.call(e) }
  else
    result
  end
end

.combinations(head, *rest) ⇒ Object

Produces an array of arrays of all possible combinations of the given arrays in the positions given. (Imagine it like a slot machine dial. This gives every combination that could come up.)

a = %w|a b|
b = %w|a x|
c = %w|x y|
Array.combinations(a, b, c).each { |x| p x }

produces

["a", "a", "x"]
["a", "a", "y"]
["a", "x", "x"]
["a", "x", "y"]
["b", "a", "x"]
["b", "a", "y"]
["b", "x", "x"]
["b", "x", "y"]

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/combination.rb', line 28

def self.combinations(head, *rest)
  crest = rest.empty? ? [[]] : combinations(*rest)
  head.inject([]) { |combs, item|
    combs + crest.map { |comb| [item] + comb }
  }
end

Instance Method Details

#**(enum) ⇒ Object

Operator alias for cross-product.

a = [1,2] ** [4,5]
a  #=> [[1, 4],[1, 5],[2, 4],[2, 5]]

CREDIT: Trans



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# File 'lib/core/facets/enumerable/cartesian.rb', line 58

def **(enum)
  Enumerable.cartesian_product(self, enum)
end

#accumulate ⇒ Object

Accumulate a set of a set.

For example, in an ORM design if Group has_many User then

groups.accumulate.users

will return a list of users from all groups.



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# File 'lib/more/facets/elementor.rb', line 58

def accumulate
  @_accumulate ||= Functor.new do |op, *args|
    inject([]) { |a, x| a << x.send(op, *args) }.flatten
  end
end

#cartesian_product(*enums, &block) ⇒ Object Also known as: cart

The instance level version of Enumerable::cartesian_product.

a = []
[1,2].cart([4,5]){|elem| a << elem }
a  #=> [[1, 4],[1, 5],[2, 4],[2, 5]]

CREDIT: Thomas Hafner



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# File 'lib/core/facets/enumerable/cartesian.rb', line 45

def cartesian_product(*enums, &block)
  Enumerable.cartesian_product(self, *enums, &block)
end

#cluster_by(&b) ⇒ Object

Similar to #group_by but returns an array of the groups. Returned elements are sorted by block.

%w{this is a test}.cluster_by {|x| x[0]}

produces

[ ['a'], ['is'], ['this', 'test'] ]

CREDIT Erik Veenstra



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# File 'lib/core/facets/enumerable/split.rb', line 78

def cluster_by(&b)
  group_by(&b).sort.transpose.pop || []   # group_by(&b).values ?
end

#collect_if(&b) ⇒ Object Also known as: map_if

Conditional collect.

[1,2,3].collect_if { |e| e > 1 }

CREDIT: ? Mauricio Fernandez



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# File 'lib/core/facets/enumerable/collect.rb', line 80

def collect_if(&b)
  a = map(&b)
  # to get the same semantics as select{|e| e}
  a.delete(false)
  a.compact!
  a
end

#collect_with_index ⇒ Object Also known as: map_with_index

Same as #collect but with an iteration counter.

a = [1,2,3].collect_with_index { |e,i| e*i }
a  #=> [0,2,6]

CREDIT: Gavin Sinclair



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# File 'lib/core/facets/enumerable/collect.rb', line 10

def collect_with_index
  r = []
  each_index do |i|
    r << yield(self[i], i)
  end
  r
end

#combos ⇒ Object

As with each_combo but returns combos collected in an array.

CREDIT: Trans



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# File 'lib/core/facets/enumerable/cartesian.rb', line 101

def combos
  a = []
  each_combo{ |c| a << c }
  a
end

#commonality(&block) ⇒ Object

Returns all items that are equal in terms of the supplied block. If no block is given objects are considered to be equal if they return the same value for Object#hash and if obj1 == obj2.

[1, 2, 2, 3, 4, 4].commonality # => { 2 => [2], 4 => [4] }

["foo", "bar", "a"].commonality { |str| str.length }
# => { 3 => ["foo, "bar"] }

# Returns all persons that share their last name with another person.
persons.collisions { |person| person.last_name }

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/probability.rb', line 105

def commonality( &block )
  had_no_block = !block
  block ||= lambda { |item| item }
  result = Hash.new { |hash, key| hash[key] = Array.new }
  self.each do |item|
    key = block.call(item)
    result[key] << item
  end
  result.reject! do |key, values|
    values.size <= 1
  end
  #return had_no_block ? result.values.flatten : result
  return result
end

#compact_collect ⇒ Object Also known as: compact_map

Collects/Maps and compacts items in one single step. The items for which the supplied block returns nil will not end up in the resulting array.

# Return telephone numbers of all persons that have a telephone number.
persons.compact_collect { |person| person.telephone_no }

Also see Enumerable#collect, Enumerable#map, Array#compact.

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/collect.rb', line 62

def compact_collect #:yield:
  filter_collect do |item|
    new_item = yield(item)
    throw(:skip) if new_item.nil?
    new_item
  end
end

#count(*c) ⇒ Object

Count the number of items in an enumerable equal (==) to the given object.

e = [ 'a', '1', 'a' ]
e.count('1')    #=> 1
e.count('a')    #=> 2

Count can also handle multiple-valued blocks.

e = { 'a' => 2, 'a' => 2, 'b' => 1 }
e.count('a',2)  #=> 1

CREDIT: Trans



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# File 'lib/core/facets/enumerable/count.rb', line 19

def count(*c)
  self.select{ |*i| i == c }.length
end

#divide(pattern) ⇒ Object

Divide on matching pattern.

['a1','b1','a2','b2'].divide(/^a/)
=> [['a1,'b1'],['a2','b2']]

CREDIT: Trans



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# File 'lib/core/facets/enumerable/split.rb', line 58

def divide(pattern)
  memo = []
  each do |obj|
    memo.push [] if pattern === obj
    memo.last << obj
  end
  memo
end

#each_by(step = nil, &yld) ⇒ Object

Iterate through slices. If slicing step is not given, the the arity if the block is used.

x = []
[1,2,3,4].each_by{ |a,b| x << [a,b] }
x  #=> [ [1,2], [3,4] ]

x = []
[1,2,3,4,5,6].each_by(3){ |a| x << a }
x  #=> [ [1,2,3], [4,5,6] ]

CREDIT: Trans



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# File 'lib/core/facets/enumerable/each.rb', line 23

def each_by(step=nil, &yld)
  if step
    each_slice(step,&yld)
  else
    step = yld.arity.abs
    each_slice(step,&yld)
  end
end

#each_combination(k = 2) ⇒ Object

Yields the block to each unique combination of n elements.

a = %w|a b c d|
a.each_combination(3) do |c|
  p c
end

produces

["a", "b", "c"]
["a", "b", "d"]
["a", "c", "d"]
["b", "c", "d"]

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/combination.rb', line 51

def each_combination(k=2)
  s = to_a
  n = s.size
  return unless (1..n) === k
  idx = (0...k).to_a
  loop do
    yield s.values_at(*idx)
    i = k - 1
    i -= 1 while idx[i] == n - k + i
    break if i < 0
    idx[i] += 1
    (i + 1 ... k).each {|j| idx[j] = idx[i] + j - i}
  end
end

#each_combo ⇒ Object

Expected to be an enumeration of arrays. This method iterates through combinations of each in position.

a = [ [0,1], [2,3] ]
a.each_combo { |c| p c }

produces

[0, 2]
[0, 3]
[1, 2]
[1, 3]

CREDIT: Trans



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# File 'lib/core/facets/enumerable/cartesian.rb', line 77

def each_combo
  a = collect{ |x|
    x.respond_to?(:to_a) ? x.to_a : 0..x
  }

  if a.size == 1
    r = a.shift
    r.each{ |n|
      yield n
    }
  else
    r = a.shift
    r.each{ |n|
      a.each_combo{ |s|
        yield [n, *s]
      }
    }
  end
end

#each_pair ⇒ Object

Iterators over each element pairing.

[:a,:b,:c,:d].each_pair { |a,b|  puts "#{a} -> #{b}" }

produces

a -> b
c -> d

CREDIT: Martin DeMello



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# File 'lib/core/facets/enumerable/each.rb', line 43

def each_pair #:yield:
  e1 = nil
  each_with_index do |e,i|
    if i % 2 == 0
      e1 = e
      next
    else
      yield(e1,e)
    end
  end
end

#each_permutation ⇒ Object

Applys a block to each possible permutation of an array/enumerable.

%w[a b c].each_permutation { |x| puts(x.join('')) }

produces

abc
acb
bac
bca
cab
cba

CREDIT: Daniel Sheppard



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# File 'lib/core/facets/enumerable/permutation.rb', line 63

def each_permutation()
    pos = Array.new(size) {|i| i}
    s = (0...size).to_a.reverse
    out = nil
    while true
        out = []
        pos.each_with_index {|p,i| out.insert(p, self[i]) }
        yield out
        break if s.each do |i|
            break if pos[i] > 0 && pos[i] -= 1
            pos[i] = i
        end
    end
end

#eachn(&block) ⇒ Object

Collect each n items based on arity.

[1,2,3,4].eachn do |x, y|
  [x,y]
end

produces

[1,2]
[3,4]

CREDIT: Martin DeMello



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# File 'lib/core/facets/enumerable/each.rb', line 68

def eachn(&block)
  n = block.arity.abs
  each_slice(n) {|i| block.call(*i)}
end

#elementwise(count = 1) ⇒ Object Also known as: ewise

Returns an elementwise Functor designed to make R-like elementwise operations possible.

[1,2].elementwise + 3          #=> [4,5]
[1,2].elementwise + [4,5]      #=> [5,7]
[1,2].elementwise + [[4,5],3]  #=> [[5,7],[4,5]

– Special thanks to Martin DeMello for helping to develop this. ++



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# File 'lib/more/facets/elementor.rb', line 128

def elementwise(count=1)
  @_elementwise_functor ||= []
  @_elementwise_functor[count] ||= Functor.new do |op,*args|
    if args.empty?
      r = self
      count.times do
        r = r.collect{ |a| a.send(op) }
      end
      r
    else
      r = args.collect do |arg|
        if Array === arg #arg.kind_of?(Enumerable)
          x = self
          count.times do
            ln = (arg.length > length ? length : arg.length )
            x = x.slice(0...ln).zip(arg[0...ln]).collect{ |a,b| a.send(op,b) }
            #slice(0...ln).zip(arg[0...1n]).collect{ |a,b| b ? a.send(op,b) : nil }
          end
          x
        else
          x = self
          count.times do
            x = x.collect{ |a| a.send(op,arg) }
          end
          x
        end
      end
      r.flatten! if args.length == 1
      r
    end
  end
end

#entropy ⇒ Object

Shannon’s entropy for an array - returns the average bits per symbol required to encode the array. Lower values mean less “entropy” - i.e. less unique information in the array.

%w{ a b c d e e e }.entropy  #=>

CREDIT: Derek



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# File 'lib/core/facets/enumerable/probability.rb', line 55

def entropy
  arr = to_a
  probHash = arr.probability
  # h is the Shannon entropy of the array
  h = -1.to_f * probHash.keys.inject(0.to_f) do |sum, i|
    sum + (probHash[i] * (Math.log(probHash[i])/Math.log(2.to_f)))
  end
  h
end

#every ⇒ Object Also known as: x, elements

Returns an elemental object. This allows you to map a method on to every element.

r = [1,2,3].every + 3  #=> [4,5,6]



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# File 'lib/more/facets/elementor.rb', line 75

def every
  @_every ||= to_elem
end

#every! ⇒ Object Also known as: x!, elements!

In place version of #every.

Raises:

  • (NoMethodError) 


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# File 'lib/more/facets/elementor.rb', line 81

def every!
  raise NoMethodError unless respond_to?(:map!)
  @_every_inplace ||= to_elem(:map!)
end

#filter_collect ⇒ Object Also known as: filter_map

Collects/Maps and filters items out in one single step. You can use throw(:skip) in the supplied block to indicate that the current item should not end up in the resulting array.

# Return names of all person with an age of at least 18.
persons.filter_collect do |person|
  throw(:skip) if person.age < 18
  person.name
end

Also see Enumerable#collect, Enumerable#find_all.

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/collect.rb', line 36

def filter_collect #:yield:
  result = []
  self.each do |item|
    catch(:skip) do
      new_item = yield(item)
      result << new_item
    end
  end
  return result
end

#frequency ⇒ Object

Generates a hash mapping each unique symbol in the array to the absolute frequency it appears.

CREDIT: Brian Schröder



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# File 'lib/core/facets/enumerable/probability.rb', line 82

def frequency
  #probs = Hash.new(0)
  #each do |e|
  #  probs[e] += 1
  #end
  #probs
  inject(Hash.new(0)){|h,v| h[v]+=1; h}
end

#group_by ⇒ Object Also known as: partition_by

#group_by is used to group items in a collection by something they have in common. The common factor is the key in the resulting hash, the array of like elements is the value.

(1..5).group_by { |n| n % 3 }
     #=> { 0 => [3], 1 => [1, 4], 2 => [2,5] }

["I had", 1, "dollar and", 50, "cents"].group_by { |e| e.class }
     #=> { String => ["I had","dollar and","cents"], Fixnum => [1,50] }

CREDIT: Erik Veenstra

TODO:

- Deprecate #group_by when released for Ruby 1.9.



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# File 'lib/core/facets/enumerable/split.rb', line 19

def group_by #:yield:
  #h = k = e = nil
  r = Hash.new
  each{ |e| (r[yield(e)] ||= []) << e }
  r
end

#ideal_entropy ⇒ Object

Returns the maximum possible Shannon entropy of the array with given size assuming that it is an “order-0” source (each element is selected independently of the next).

CREDIT: Derek



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# File 'lib/core/facets/enumerable/probability.rb', line 71

def ideal_entropy
  arr = to_a
  unitProb = 1.0.to_f / arr.size.to_f
  (-1.to_f * arr.size.to_f * unitProb * Math.log(unitProb)/Math.log(2.to_f))
end

#inject!(s) ⇒ Object

Say you want to count letters–

some_text.inject!(Hash.new(0)) {|h,l| h[l] += 1}

vs

 some_text.inject(Hash.new(0)) {|h,l| h[l] +=1; h}

CREDIT: David Black



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# File 'lib/core/facets/enumerable/collect.rb', line 125

def inject!(s)
  k = s
  each { |i| yield(k, i) }
  k
end

#injecting(s) ⇒ Object

Say you want to count letters–

some_text.injecting(Hash.new(0)) {|h,l| h[l] += 1}

vs

some_text.inject(Hash.new(0)) {|h,l| h[l] +=1; h}

This may be deprecated in favor of inject!. We make both available for now to make sure (via the test of time) that they are 100% equivalent.

CREDIT: Louis J Scoras



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# File 'lib/core/facets/enumerable/collect.rb', line 145

def injecting(s)
  inject(s) do |k, i|
    yield(k, i); k
  end
end

#map_send(meth, *args) ⇒ Object

Send a message to each element and collect the result.

CREDIT: Sean O'Halpin



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# File 'lib/core/facets/enumerable/collect.rb', line 96

def map_send(meth, *args) #:yield:
  if block_given?
    map{|e| yield(e.send(meth, *args))}
  else
    map{|e| e.send(meth, *args)}
  end
end

#mash(&yld) ⇒ Object Also known as: graph, collate

Like #map/#collect, but generates a Hash. The block is expected to return two values: the key and the value for the new hash.

numbers  = (1..3)
squares  = numbers.mash { |n| [n, n*n] }   # { 1=>1, 2=>4, 3=>9 }
sq_roots = numbers.mash { |n| [n*n, n] }   # { 1=>1, 4=>2, 9=>3 }

CREDIT: Trans CREDIT: Andrew Dudzik (adudzik)

NOTE: Would #correlate would be better?



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# File 'lib/core/facets/enumerable/mash.rb', line 17

def mash(&yld)
  if yld
    inject({}) do |h, *kv| # Used to be inject({}) do |h,kv|
      r = *yld[*kv]        # The *-op works differnt from to_a on single element hash!!!
      nk, nv = *r          # Used to be nk, nv = *yld[*kv].to_a.flatten
      h[nk] = nv
      h
    end
  else
    Enumerator.new(self,:graph)  # Used to be Hash[*self.to_a] or Hash[*self.to_a.flatten]
  end
end

#mode ⇒ Object

In Statistics mode is the value that occurs most frequently in a given set of data.

CREDIT: Trans



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# File 'lib/core/facets/enumerable/probability.rb', line 8

def mode
  count = Hash.new(0)
  each {|x| count[x] += 1 }
  count.sort_by{|k,v| v}.last[0]
end

#modulate(modulo) ⇒ Object

Modulate. Divide an array into groups by modulo of the index.

2,4,6,8].modulate(2) #=> [[2,6],

CREDIT: Trans

NOTE: Would this be better named ‘collate’?

Raises:

  • (ArgumentError) 


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# File 'lib/core/facets/enumerable/split.rb', line 90

def modulate(modulo)
  return to_a if modulo == 1
  raise ArgumentError, 'bad modulo' if size % modulo != 0
  r = Array.new(modulo, [])
  (0...size).each do |i|
    r[i % level] += [self[i]]
  end
  r
end

#none? ⇒ Boolean

Enumerable#none? is the logical opposite of the builtin method Enumerable#any?. It returns true if and only if none of the elements in the collection satisfy the predicate.

If no predicate is provided, Enumerable#none? returns true if and only if none of the elements have a true value (i.e. not nil or false).

[].none?                      # true
[nil].none?                   # true
[5,8,9].none?                 # false
(1...10).none? { |n| n < 0 }  # true
(1...10).none? { |n| n > 0 }  # false

CREDIT: Gavin Sinclair

Returns:

  • (Boolean) 


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# File 'lib/core/facets/enumerable/count.rb', line 70

def none?  # :yield: e
  if block_given?
    not self.any? { |e| yield e }
  else
    not self.any?
  end
end

#nonuniq ⇒ Object Also known as: duplicates

Returns a list on non-unique,

[1,1,2,2,3,4,5].nonuniq  #=> [1,2]

CREDIT: Martin DeMello



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# File 'lib/core/facets/enumerable/count.rb', line 133

def nonuniq
  h1 = {}
  h2 = {}
  each {|i|
    h2[i] = true if h1[i]
    h1[i] = true
  }
  h2.keys
end

#occur(n = nil) ⇒ Object

Returns an array of elements for the elements that occur n times. Or according to the results of a given block.

[1,1,2,3,3,4,5,5].occur(1)             #=> [2,4]
[1,1,2,3,3,4,5,5].occur(2)             #=> [1,3,5]
[1,1,2,3,3,4,5,5].occur(3)             #=> []

[1,2,2,3,3,3].occur(1..1)              #=> [1]
[1,2,2,3,3,3].occur(2..3)              #=> [2,3]

[1,1,2,3,3,4,5,5].occur { |n| n == 1 } #=> [2,4]
[1,1,2,3,3,4,5,5].occur { |n| n > 1 }  #=> [1,3,5]

CREDIT: ?



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# File 'lib/core/facets/enumerable/count.rb', line 95

def occur(n=nil) #:yield:
  result = Hash.new { |hash, key| hash[key] = Array.new }
  self.each do |item|
    key = item
    result[key] << item
  end
  if block_given?
    result.reject! { |key, values| ! yield(values.size) }
  else
    raise ArgumentError unless n
    if Range === n
      result.reject! { |key, values| ! n.include?(values.size) }
    else
      result.reject! { |key, values| values.size != n }
    end
  end
  return result.values.flatten.uniq
end

#one? ⇒ Boolean

Enumerable#one? returns true if and only if exactly one element in the collection satisfies the given predicate.

If no predicate is provided, Enumerable#one? returns true if and only if exactly one element has a true value (i.e. not nil or false).

[].one?                      # false
[nil].one?                   # false
[5].one?                     # true
[5,8,9].one?                 # false
(1...10).one? { |n| n == 5 } # true
(1...10).one? { |n| n < 5 }  # false

CREDIT: Gavin Sinclair

Returns:

  • (Boolean) 


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# File 'lib/core/facets/enumerable/count.rb', line 39

def one?  # :yield: e
  matches = 0
  if block_given?
    self.each do |e|
      if yield(e)
        matches += 1
        return false if matches > 1
      end
    end
    return (matches == 1)
  else
    one? { |e| e }
  end
end

#permutation(number) ⇒ Object Also known as: permute

Permutation proves the possible orders of an enumerable. Each is index by a permutation number. The maximum number of arrangements is the factorial of the size of the array.

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/permutation.rb', line 11

def permutation(number)
    arr = to_a
    out = arr[0..0]
    nextfactor = factor = 1
    arr.each_with_index {|x,i|
        case i
        when 0
          next
        else
            nextfactor = factor * (i+1)
            out.insert(number % nextfactor / factor, x)
            factor = nextfactor
        end
    }
    out
end

#permutation_number(original_array = self.to_a.sort) ⇒ Object

Calculate permutation number.

CREDIT: Florian Gross



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# File 'lib/core/facets/enumerable/permutation.rb', line 34

def permutation_number(original_array=self.to_a.sort)
    arr = to_a
    m = 1
    v = 0
    last_indicies = Hash.new(0)
    original_array.each_with_index {|x,i|
        next if i==0
        m *= i
        done = original_array[0..i]
        v += m * arr.select {|y| done.include?(y)}.rindex(x)
    }
    v
end

#probability ⇒ Object

Generates a hash mapping each unique symbol in the array to the relative frequency, i.e. the probablity, of it appearence.

CREDIT: Brian Schröder



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# File 'lib/core/facets/enumerable/probability.rb', line 20

def probability
  probs = Hash.new(0.0)
  size = 0.0
  each do | e |
    probs[e] += 1.0
    size += 1.0
  end
  probs.keys.each{ |e| probs[e] /= size }
  probs
end

#split(pattern) ⇒ Object

Split on matching pattern. Unlike #divide this does not include matching elements.

['a1','a2','b1','a3','b2','a4'].split(/^b/)
=> [['a1','a2'],['a3'],['a4']]

CREDIT: Trans



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# File 'lib/core/facets/enumerable/split.rb', line 39

def split(pattern)
  memo = []
  each do |obj|
    if pattern === obj
      memo.push []
    else
      memo.last << obj
    end
  end
  memo
end

#sum ⇒ Object

Uses #+ to sum the enumerated elements.

[1,2,3].sum  #=> 6
[3,3,3].sum  #=> 9

CREDIT: Gavin Kistner



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# File 'lib/core/facets/enumerable/count.rb', line 121

def sum
  v = 0
  each{ |n| v+=n }
  v
end

#threaded_map ⇒ Object

Like Enumerable#map but each iteration is processed via a separate thread.

CREDIT Sean O’Halpin



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# File 'lib/more/facets/thread.rb', line 38

def threaded_map #:yield:
  map{|e| Thread.new(e){|t| yield t}}.map_send(:value)
end

#threaded_map_send(meth, *args) ⇒ Object

Like Enumerable#map_send but each iteration is processed via a separate thread.

CREDIT Sean O’Halpin



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# File 'lib/more/facets/thread.rb', line 47

def threaded_map_send(meth, *args) #:yield:
  if block_given?
    map{|e| Thread.new(e){|t| yield t.send(meth, *args)}}.map_send(:value)
  else
    map{|e| Thread.new(e){|t| t.send(meth, *args)}}.map_send(:value)
  end
end

#to_elem(meth = nil) ⇒ Object

Create Elementor.



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# File 'lib/more/facets/elementor.rb', line 66

def to_elem(meth=nil)
  Elementor.new(self, meth || :map)
end

#to_h(arrayed = nil) ⇒ Object

Convert an Enumerable object into a hash bu first turning it into an array.

CREDIT: Trans



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# File 'lib/core/facets/conversion.rb', line 129

def to_h(arrayed=nil)
  to_a.to_h(arrayed)
end

#to_hash(&blk) ⇒ Object

Produces a hash from an Enumerable with index for keys.

enu = 'a'..'b'
enu.to_hash  #=> { 0=>'a', 1=>'b' }

If a block is passed, the hash values will be set by calling the block with the enumerated element and it’s counter.

enu = 'a'..'b'
enu.to_hash{ |e,i| e }  #=> { 0=>'a', 1=>'b' }

See also #mash.

CREDIT: Trans



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# File 'lib/core/facets/conversion.rb', line 114

def to_hash( &blk )
  h = {}
  if blk
    each_with_index{ |e,i| h[i] = blk.call(e,i) }
  else
    each_with_index{ |e,i| h[i] = e }
  end
  h
end

#uniq_by ⇒ Object

Like #uniq, but determines uniqueness based on a given block.

(-5..5).to_a.uniq_by {|i| i*i }

produces

[-5, -4, -3, -2, -1, 0]

CREDIT: ?



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# File 'lib/core/facets/enumerable/count.rb', line 171

def uniq_by #:yield:
  h = {}; inject([]) {|a,x| h[yield(x)] ||= a << x}
end