Simplest code to sort arrays in ruby?

Question

I usually do something like

array.sort{|a,b| a.something <=> b.something}

How should I DRY this up?

Answer 1

use sort_by

array.sort_by{|e| e.something}

or

sort_lambda = lambda{|e| e.something}
array.sort_by(&sort_lambda)

With latter you can reuse sort_lambda in other sort_by statements

Answer 2

In Rails, or rather with ActiveSupport, or in Ruby 1.9 (possibly 1.8.7, not sure) you can use the new short-cut hotness:

array.sort_by(&:something)

Note that sort_by has possibly expensive (and possibly beneficial: it depends on sort key complexity) side-effects: it generates and stores a temporary key-value pair for each item so that it can sort by your new key. See the discussion in the documentation for more on this.

Answer 3

+1 to both of Eimantas' suggestions, but I often have this come up in cases where I have a custom class that always sorts this way, like Albums that should sort case-insensitively, ignoring leading punctuation and the/a/an. For that use it's more efficient to calculate the sort value once, and then redefine <=> accordingly. E.g.:

class Album
 def sort_value
    @sv ||= @name.downcase.sub(/^\W*(the|an|a) /,"")
  end

  def <=>(other)
    sort_value <=> (other.sort_value rescue other)
  end
end

Answer 4

Have you considered including Comparable in the class for a and b, and just calling sort?