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You can use the sort method on an array, hash, or another Enumerable object & you'll get the default sorting behavior (sort based on <=> operator) You can use sort with a block, and two block arguments, to define how one object is different than another (block should return 1, 0, or -1)
To sort an array of objects, you use the sort() method and provide a comparison function that determines the order of objects.
Sorting Hashes in RubyTo sort a hash in Ruby without using custom algorithms, we will use two sorting methods: the sort and sort_by. Using the built-in methods, we can sort the values in a hash by various parameters.
rsort() - sort arrays in descending order. asort() - sort associative arrays in ascending order, according to the value. ksort() - sort associative arrays in ascending order, according to the key. arsort() - sort associative arrays in descending order, according to the value.
I recommend using sort_by instead:
objects.sort_by {|obj| obj.attribute}
Especially if attribute may be calculated.
Or a more concise approach:
objects.sort_by(&:attribute)
Yes, using Array#sort! this is easy.
myarray.sort! { |a, b| a.attribute <=> b.attribute }
Ascending order :
objects_array.sort! { |a, b| a.attribute <=> b.attribute }
or
objects_array.sort_by{ |obj| obj.attribute }
Descending order :
objects_array.sort! { |a, b| b.attribute <=> a.attribute }
or
objects_array.sort_by{ |obj| obj.attribute }.reverse
in case you need sorting by two attributes, where first one is more important then second (means taking in account second arguments only if first arguments are equal), then you may do like this
myarray.sort{ |a,b| (a.attr1 == b.attr1) ? a.attr2 <=> b.attr2 : a.attr1 <=> b.attr1 }
or in case of array of arrays
myarray.sort{ |a,b| (a[0] == b[0]) ? a[1] <=> b[1] : a[0] <=> b[0] }
You can make any class sortable by overriding the <=> method:
class Person
attr_accessor :first_name, :last_name
def initialize(first_name, last_name)
@first_name = first_name
@last_name = last_name
end
def <=>(other)
@last_name + @first_name <=> other.last_name + other.first_name
end
end
Now an array of Person objects will be sortable on last_name.
ar = [Person.new("Eric", "Cunningham"), Person.new("Homer", "Allen")]
puts ar # => [ "Eric Cunningham", "Homer Allen"] (Person objects!)
ar.sort!
puts ar # => [ "Homer Allen", "Eric Cunningham" ]
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