Sort hash by key, return hash in Ruby

In Ruby 2.1 it is simple:

h.sort.to_h

Note: Ruby >= 1.9.2 has an order-preserving hash: the order keys are inserted will be the order they are enumerated. The below applies to older versions or to backward-compatible code.

There is no concept of a sorted hash. So no, what you're doing isn't right.

If you want it sorted for display, return a string:

"{" + h.sort.map{|k,v| "#{k.inspect}=>#{v.inspect}"}.join(", ") + "}"

or, if you want the keys in order:

h.keys.sort

or, if you want to access the elements in order:

h.sort.map do |key,value|
  # keys will arrive in order to this block, with their associated value.
end

but in summary, it makes no sense to talk about a sorted hash. From the docs, "The order in which you traverse a hash by either key or value may seem arbitrary, and will generally not be in the insertion order." So inserting keys in a specific order into the hash won't help.

I've always used sort_by. You need to wrap the #sort_by output with Hash[] to make it output a hash, otherwise it outputs an array of arrays. Alternatively, to accomplish this you can run the #to_h method on the array of tuples to convert them to a k=>v structure (hash).

hsh ={"a" => 1000, "b" => 10, "c" => 200000}
Hash[hsh.sort_by{|k,v| v}] #or hsh.sort_by{|k,v| v}.to_h

There is a similar question in "How to sort a Ruby Hash by number value?".

Sort hash by key, return hash in Ruby

With destructuring and Hash#sort

hash.sort { |(ak, _), (bk, _)| ak <=> bk }.to_h

Enumerable#sort_by

hash.sort_by { |k, v| k }.to_h

Hash#sort with default behaviour

h = { "b" => 2, "c" => 1, "a" => 3  }
h.sort         # e.g. ["a", 20] <=> ["b", 30]
hash.sort.to_h #=> { "a" => 3, "b" => 2, "c" => 1 }

Note: < Ruby 2.1

array = [["key", "value"]] 
hash  = Hash[array]
hash #=> {"key"=>"value"}

Note: > Ruby 2.1

[["key", "value"]].to_h #=> {"key"=>"value"}

You gave the best answer to yourself in the OP: Hash[h.sort] If you crave for more possibilities, here is in-place modification of the original hash to make it sorted:

h.keys.sort.each { |k| h[k] = h.delete k }

No, it is not (Ruby 1.9.x)

require 'benchmark'

h = {"a"=>1, "c"=>3, "b"=>2, "d"=>4}
many = 100_000

Benchmark.bm do |b|
  GC.start

  b.report("hash sort") do
    many.times do
      Hash[h.sort]
    end
  end

  GC.start

  b.report("keys sort") do
    many.times do
      nh = {}
      h.keys.sort.each do |k|
        nh[k] = h[k]
      end
    end
  end
end

       user     system      total        real
hash sort  0.400000   0.000000   0.400000 (  0.405588)
keys sort  0.250000   0.010000   0.260000 (  0.260303)

For big hashes difference will grow up to 10x and more

ActiveSupport::OrderedHash is another option if you don't want to use ruby 1.9.2 or roll your own workarounds.

You can use sort method and then convert array back to hash with to_h method

h = { "a" => 1, "c" => 3, "b" => 2, "d" => 4 }
h.sort.to_h
# => { "a" => 1, "b" => 2, "c" => 3, "d" => 4 }

@ordered = {}
@unordered.keys.sort.each do |key|
  @ordered[key] = @unordered[key]
end

I had the same problem ( I had to sort my equipments by their name ) and i solved like this:

<% @equipments.sort.each do |name, quantity| %>
...
<% end %>

@equipments is a hash that I build on my model and return on my controller. If you call .sort it will sort the hash based on it's key value.

I borrowed Boris Stitnicky's inspired solution to patch an in-place sort! method into Hash:

def sort!
  keys.sort!.each { |k| store k, delete(k) }
  self
end

I liked the solution in the earlier post.

I made a mini-class, called it class AlphabeticalHash. It also has a method called ap, which accepts one argument, a Hash, as input: ap variable. Akin to pp (pp variable)

But it will (try and) print in alphabetical list (its keys). Dunno if anyone else wants to use this, it's available as a gem, you can install it as such: gem install alphabetical_hash

For me, this is simple enough. If others need more functionality, let me know, I'll include it into the gem.

EDIT: Credit goes to Peter, who gave me the idea. :)