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Ruby Array Manipulations

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We will be discussing some built-in functions in Ruby.Most of them are used to fix the logical challenges in Ruby Programing.

select

  • used to filter the collections.
  • return type will be an array
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  [1, 2, 3, 4, 5].select{ |i| i > 3 }

  #=> [4, 5]

detect

  • will return the first matched value
  • returned value will be a single element
  [1, 2, 3, 4, 5].detect{ |i| i > 3 }

  #=> 4

reject

  • will be the opposite of the select
  • will be an array
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  [1, 2, 3, 4, 5].reject{ |i| i > 3 }

  #=> [1, 2, 3]

equality operator

  • denoted by ===
  • more used in the case of Reg ex and range
  (1..3) === 2

  #=> true

  (1..3) === 4

  #=> false

  /el/ === 'Hello World'

  #=> false
  • LHS should be Range or REGEX and RHS will be the specific object.

grep

  • same use in the case of grep
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  [6, 14, 28, 47, 12].grep(5..15)

  #=> [6, 14, 12]
  • we have an array like [1, ‘a’, ‘b’, 2]
  • if we do the [1, 'a', 'b', 2].map(&:upcase)
  • will raise an error
  • we can fix those by grep
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  [1, 'a', 'b', 2].grep(String, &:upcase)

  #=> ['A', 'B']

sort

  • if we have integer and strings in the array .sort command will fail.
  • we can clear this issue by using the sort_by method.
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  ['5', '2', 3, '1'].sort_by(&:to_i)

  #=> ['1', '2', 3, '5']

all?

  • return true if all values are true
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  [2, 4, 6, 8].all?(&:even?)

  #=> true

any?

  • return true if any of the value is true.
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  [2, 3, 5, 9].any?(&:even?)

  #=> true

reduce

  • create a sum of the array
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  [1, 2, 3].reduce(:+)

  #=> 6

another interested methods are cycle, next, reverse_cycle

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