Ruby Method of the Day - Array.reject

Posted by Kelly McCauley on Nov 20, 2007

Signature

array.reject {|element| block}    #=> new_array

array.reject {|element| block} iterates over array’s elements and returns new_array that contains any element in array where the block returns either nil or false.

Examples

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a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

a.reject {|n| nil}                        #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a.reject {|n| false}                      #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a.reject {|n| true}                       #=> []
a.reject {|n| ''}                         #=> []
a.reject {|n| 0}                          #=> []

a.reject {|n| n == 3}                     #=> [1, 2, 4, 5, 6, 7, 8, 9, 10]
a.reject {|n| n % 2 == 0 }                            #=> [1, 3, 5, 7, 9]
a.reject {|n| true if (n % 3 == 0) || (n % 5 == 0) }  #=> [1, 2, 4, 7, 8]

Documentation Reference

Ruby version 1.8.6

www.ruby-doc.org : Array.reject

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