Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/rubyplb.rb,
lib/rubyplb/ary_with_combination.rb

Constant Summary collapse

@@combi_indices_hash = 
{}

Instance Method Summary collapse

Instance Method Details

#combi_indices(s, n) ⇒ Object 



4
5
6
7
8
9
10
11
12
13
14
15
 
# File 'lib/rubyplb/ary_with_combination.rb', line 4

def combi_indices(s,n)
  ret = @@combi_indices_hash[s] ||= []
  if ret.empty?
    s.times{|i|
      ret.dup.each{|a|
        ret.push(a+[i])
      }
      ret.push([i])
    }
  end
  ret.select{|a|a.size==n}
end

#combination(n) ⇒ Object 



17
18
19
20
 
# File 'lib/rubyplb/ary_with_combination.rb', line 17

def combination(n)
  # combination of Ruby 1.9.x returns array with a blank array as its top
  combi_indices(self.size,n).collect{|a| self.values_at(*a)}.unshift([])
end

#subset ⇒ Object 



26
27
28
29
30
 
# File 'lib/rubyplb.rb', line 26

def subset
  (0..self.length).inject([]) do |ret, n|
    ret.push(*self.combination(n))
  end
end

#subsets ⇒ Object 



22
23
24
25
26
 
# File 'lib/rubyplb/ary_with_combination.rb', line 22

def subsets
  (0..length).inject([]) do |ret, n|
    ret.push(*combination(n))
  end.uniq
end

#true_subsets ⇒ Object 



28
29
30
31
32
 
# File 'lib/rubyplb/ary_with_combination.rb', line 28

def true_subsets
  (1..length).inject([]) do |ret, n|
    ret.push(*combination(n))
  end.uniq
end