Sort hash by key, return hash in Ruby

Would this be the best way to sort a hash and return Hash object (instead of Array):

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

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

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?".