Module: Random::ArrayExtensions

Included in:
Array
Defined in:
lib/standard/facets/random.rb

Overview

Random extensions for Array class.

Instance Method Summary collapse

Instance Method Details

#at_rand ⇒ Object

Deprecated.

Use Array#sample instead.



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# File 'lib/standard/facets/random.rb', line 120

def at_rand
  warn "Array#at_rand is deprecated. Use Array#sample instead.", uplevel: 1
  sample
end

#at_rand! ⇒ Object

Deprecated.

Use Array#sample! instead.



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# File 'lib/standard/facets/random.rb', line 126

def at_rand!
  warn "Array#at_rand! is deprecated. Use Array#sample! instead.", uplevel: 1
  sample!
end

#pick(n = nil) ⇒ Object

Deprecated.

Use Array#sample instead.



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# File 'lib/standard/facets/random.rb', line 132

def pick(n=nil)
  warn "Array#pick is deprecated. Use Array#sample instead.", uplevel: 1
  n ? sample(n) : sample
end

#pick!(n = nil) ⇒ Object

Deprecated.

Use Array#sample! instead.



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# File 'lib/standard/facets/random.rb', line 138

def pick!(n=nil)
  warn "Array#pick! is deprecated. Use Array#sample! instead.", uplevel: 1
  sample!(n)
end

#rand_index ⇒ Object

Random index.



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# File 'lib/standard/facets/random.rb', line 145

def rand_index
  Random.number(size)
end

#rand_subarrays(n = 1) ⇒ Object

Generates random subarrays. Uses random numbers and bit- fiddling to assure performant uniform distributions even for large arrays.

a = *1..5
a.rand_subarrays(2) #=> [[3, 4, 5], []]
a.rand_subarrays(3) #=> [[1], [1, 4, 5], [2, 3]]

CREDIT: Michael Kohl

Raises:

  • (ArgumentError) 


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# File 'lib/standard/facets/random.rb', line 176

def rand_subarrays(n=1)
  raise ArgumentError, "negative argument" if n < 0
  (1..n).map do
    r = rand(2**self.size)
    self.select.with_index { |_, i| r[i] == 1 }
  end
end

#rand_subset(number = nil, exclusive = true) ⇒ Object

Returns a random subset of an Array. If a number of elements is specified then returns that number of elements, otherwise returns a random number of elements upto the size of the Array.

[1, 2, 3, 4].rand_subset(1)        #~> [2]
[1, 2, 3, 4].rand_subset(4)        #~> [2, 1, 3, 4]
[1, 2, 3, 4].rand_subset           #~> [1, 3, 4]
[1, 2, 3, 4].rand_subset           #~> [2, 3]


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# File 'lib/standard/facets/random.rb', line 159

def rand_subset(number=nil, exclusive=true)
  number = Random.number(size) unless number
  number = number.to_int
  return sort_by{rand}.slice(0,number) if exclusive
  ri =[]; number.times { |n| ri << Random.number(size) }
  return values_at(*ri)
end

#sample!(n = nil) ⇒ Object

Destructive version of Array#sample. Removes and returns a random element, or n random exclusive elements.

a = [1,2,3,4]
a.sample!        #~> 2
a                #~> [1,3,4]

a = [1,2,3,4,5]
a.sample!(3)     #~> [2,4,1]
a                #~> [3,5]


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# File 'lib/standard/facets/random.rb', line 103

def sample!(n=nil)
  if n
    if n > self.size
      r = self.dup
      self.replace([])
      r
    else
      r = []
      n.times { r << delete_at(Random.number(size)) }
      r
    end
  else
    delete_at(Random.number(size))
  end
end