method
uniq
v2_5_5 -
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- Class:
Array
uniq()public
Returns a new array by removing duplicate values in self.
If a block is given, it will use the return value of the block for comparison.
It compares values using their #hash and #eql? methods for efficiency.
self is traversed in order, and the first occurrence is kept.
a = [ "a", "a", "b", "b", "c" ] a.uniq # => ["a", "b", "c"] b = [["student","sam"], ["student","george"], ["teacher","matz"]] b.uniq { |s| s.first } # => [["student", "sam"], ["teacher", "matz"]]
2Notes
custom uniq method
Build hash from elements of your Array using attribute as key and the element as value and return values of Hash:
Hash[*ary.map {|obj| [obj.name, obj]}.flatten].values
Pass a block
While this example is not so obvious on first look what the block passed does, here's a small explanation:
when the block is passed to this function, the uniqueness is checked based on a value returned by that block.
For example if it's array of objects with "user_id" method, then this would be:
tasks.uniq{|t| t.user_id } # returns only tasks with unique user_id