Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/list-utils.rb

Overview

Adds several syntactic sugar methods and method aliases, inspired by CPAN’s List::Util and List::MoreUtils modules, and the Haskell 98 Standard Prelude.

Instance Method Summary collapse

Instance Method Details

#drop(count) ⇒ Object

Returns a copy of the Array with the first count items missing.



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# File 'lib/list-utils.rb', line 9

def drop(count)
  self[ count .. -1 ]
end

#drop_until(&blk) ⇒ Object Also known as: take_while

Returns a copy of the Array from the first point at which &blk is true to the end.



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# File 'lib/list-utils.rb', line 22

def drop_until(&blk)
  return self if yield head
  tail ? tail.drop_until(&blk) : []
end

#drop_while(&blk) ⇒ Object Also known as: take_until

Returns a copy of the Array from the first point at which &blk is false to the end.



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# File 'lib/list-utils.rb', line 15

def drop_while(&blk)
  return self unless yield head
  tail ? tail.drop_while(&blk) : []
end

#false_count(&blk) ⇒ Object

Returns the number of elements for which &blk is false.



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# File 'lib/list-utils.rb', line 30

def false_count(&blk)
  size - true_count(&blk)
end

#fold(method_sym) ⇒ Object Also known as: reduce

Performs the method identified by method_sym on each element with the following element as the single argument.

  • (0..9).to_a.fold(:+) = 45

  • [0, 1].fold(:+) = 1

  • [0, 1].fold(:*) = 0

  • ‘hello’.split(”).fold(:+) = ‘hello’



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# File 'lib/list-utils.rb', line 43

def fold(method_sym)
  output = first
  (self - [first]).each do |e|
    output = output.send(method_sym, e)
  end
  output
end

#none?(&blk) ⇒ Boolean

Returns true if none of the elements satisfy &blk, false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/list-utils.rb', line 55

def none?(&blk) 
  not any?(&blk)
end

#not_all?(&blk) ⇒ Boolean

Returns true if any of the elements do not satisfy &blk, false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/list-utils.rb', line 61

def not_all?(&blk) 
  not all?(&blk)
end

#rand_element ⇒ Object

Returns a randomly-chosen element of the Array.



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# File 'lib/list-utils.rb', line 66

def rand_element
  shuffle[0]
end

#rest ⇒ Object Also known as: tail

Returns all elements of the Array in order except the first.



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# File 'lib/list-utils.rb', line 73

def rest
  self[ 1 .. -1 ]
end

#shuffle ⇒ Object

Returns a copy of the Array in random order.



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# File 'lib/list-utils.rb', line 78

def shuffle
  sort_by { rand }
end

#sum ⇒ Object

Syntactic sugar for fold(:+).



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# File 'lib/list-utils.rb', line 83

def sum
  fold(:+)
end

#take(count) ⇒ Object

Returns the first count elements of the Array.



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# File 'lib/list-utils.rb', line 90

def take(count)
  self[0 .. (count-1) ]
end

#true_count(&blk) ⇒ Object

Returns the number of elements for which &blk is true.



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# File 'lib/list-utils.rb', line 98

def true_count(&blk)
  filter(&blk).size
end