fastruby
Add Array#sort.reverse vs Array#sort_by with block
arr.reverse.sort simply makes no sense. Array#reverse returns reverse-ordered copy of an array.
Comparing sort_by { |a| -a } to sort_by(&:-@) was already covered in:
https://github.com/JuanitoFatas/fast-ruby/blob/master/code/enumerable/sort-vs-sort_by.rb
Comparing sort { |a, b| b <=> a } to sort_by(&:-@) is also pointless as it's already covered by the above.
Should really be compared with sort_by{ |a| -a }or sort_by(&:-@)
@semaperepelitsa agreed. Updated.
arr.reverse.sort simply makes no sense.
@ixti typo, should be arr.sort.reverse. Fixed.
Comparing sort_by { |a| -a } to sort_by(&:-@) was already covered in:
@ixti yes I know, I wrote it. This PR differs by 50%.
Did you mean, sort.reverse!?
@ParadoxV5 yes updated (though no !)
Though technically this is comparing Array#sort etc... not Enumerable. Updated.
though no
!
@sshaw Not sure if the sort! variant is faster or not because several other languages (including our rival Python) do their sorting in-place (modifying the original). (reverse and sort each creates a new array with reversed contents.)
Also, should compare with _2 <=> _1 because Numeric happens to have negation functionality (@-), but not guaranteed any ~~Comparable~~ duck-type with <=>, such as Strings (@- doesn’t negate) and Arrays (@- isn’t defined). (P.P.S Though we can include Numeric reverse-sorting separately as a special case.)
P.S. @ixti The above file does not sort reversedly.
I still think this comparison is weird and very niche - it has meaning only when the object is an Array of Numbers. In which case the bet variant will be: arr.sort.tap(&:reverse!), in other cases it will either fail or will give unexpected result.
@ParadoxV5 I know that the sort-vs-sort_by.rb has no reverse sorting.