How to Sort a Ruby Hash by Number Value

How to sort a Ruby Hash by number value?

No idea how you got your results, since it would not sort by string value... You should reverse a1 and a2 in your example

Best way in any case (as per Mladen) is:

metrics = {"sitea.com" => 745, "siteb.com" => 9, "sitec.com" => 10 }
metrics.sort_by {|_key, value| value}
  # ==> [["siteb.com", 9], ["sitec.com", 10], ["sitea.com", 745]]

If you need a hash as a result, you can use to_h (in Ruby 2.0+)

metrics.sort_by {|_key, value| value}.to_h
  # ==> {"siteb.com" => 9, "sitec.com" => 10, "sitea.com", 745}

How to sort a hash by value in descending order and output a hash in ruby?

Try:

Hash[h.sort.reverse]

This should return what you want.

Edit:

To do it by value:

Hash[h.sort_by{|k, v| v}.reverse]

How to sort hash keys by their value in ruby 2.3.0

You can't change the order of a hash, but you can sort the array before turning it into a hash:

data = [
  ['Frank', 33],
  ['Stacy', 15],
  ['Juan', 24],
  ['Dom', 32],
  ['Steve', 24],
  ['Jill', 24]
]

hash = data.sort_by(&:last).to_h
# => { "Stacy" => 15,
#      "Juan" => 24,
#      "Steve" => 24,
#      "Jill" => 24,
#      "Dom" => 32,
#      "Frank" => 33 }

If you already have a hash, then you'll have to turn it into an array, then sort it, and then turn it back into a hash, e.g. hash.to_a.sort_by(&:last).to_h.

Sorting Hash by value

Enumerable#sort_by never promised to sort the enumerable inplace. It returns the result:

puts mapa.sort_by {|a,b| -b}
#⇒ sorted

or, in more idiomatic manner:

mapa.sort_by(&:last).reverse.each do |k, v|
  puts ...
end

Please note, that when examining the output in irb, the order might not correspond to the real order of elements in a hash, since irb (with print formatters installed) has it’s own ideas on how to output hashes.

How to sort a hash by the values of another array in Ruby?

You don't need to sort anything, and you also don't need to create a lookup table. Your array is already sorted the way you want and your sort_me hash is already a lookup table:

elements = ['one', 'two', 'three']
# => ["one", "two", "three"]
sort_me = {'three' => 3, 'two' => 2, 'one' => 1}
# => {"three"=>3, "two"=>2, "one"=>1}
elements.map{|key| [key, sort_me[key] ] }.to_h
# => {"one"=>1, "two"=>2, "three"=>3}

If you want to use symbols and strings:

elements = ['one', 'two', 'three']
# => ["one", "two", "three"]
sort_me = {three: 3, two: 2, one: 1}
# => {:three=>3, :two=>2, :one=>1}
elements.map{|key| [key.to_sym, sort_me[key.to_sym] ] }.to_h
# => {:one=>1, :two=>2, :three=>3}

Finally, if some elements are not used in the hash, you could simply remove pairs with nil values:

elements = ['one', 'two', 'two_and_a_half', 'three']
# => ["one", "two", "two_and_a_half", "three"]
elements.map{|key| [key.to_sym, sort_me[key.to_sym] ] }.to_h
# => {:one=>1, :two=>2, :two_and_a_half=>nil, :three=>3}
elements.map{|key| [key.to_sym, sort_me[key.to_sym] ] }.reject{|k, v| v.nil? }.to_h
# => {:one=>1, :two=>2, :three=>3} 

Sorting a Hash by integer value of hash key in Ruby 1.9

Nice and simple (for 1.9):

hs = Hash[h.sort_by {|k,v| k.to_i }]

For example:

>> h = { '23' => 'twenty three', '11' => 'eleven', '42' => 'forty two', '1' => 'one' }
=> {"23"=>"twenty three", "11"=>"eleven", "42"=>"forty two", "1"=>"one"}
>> hs = Hash[h.sort_by {|k,v| k.to_i }]
=> {"1"=>"one", "11"=>"eleven", "23"=>"twenty three", "42"=>"forty two"}

And for more recent Rubies:

hs = h.sort_by { |k, _| k.to_i }.to_h

How to sort a hash by values

You can use ActiveSupport::OrderedHash for Ruby 1.8:

ActiveSupport::OrderedHash implements a hash that preserves insertion order, as in Ruby 1.9

I don't have 1.8.6 running, but this should work:

a = {}
a[0] = "c"
a[1] = "b"
a[2] = "a"

ordered = ActiveSupport::OrderedHash[*a.sort_by{|k,v| v}.flatten]
ordered.keys
# => [2, 1, 0], this order is guaranteed

As noted in the quote above hashes in Ruby 1.9 "enumerate their values in the order that the corresponding keys were inserted", so this is only needed for Ruby 1.8.

Sorting a hash in Ruby by its value first then its key

Try this:

Assuming:

a = { 
  'the' => '6', 
  'we' => '7', 
  'those' => '5', 
  'have' => '3', 
  'hav' => '3', 
  'haven' => '3'
}

then after doing this:

b = a.sort_by { |x, y| [ -Integer(y), x ] }

b will look like this:

[
  ["we", "7"], 
  ["the", "6"], 
  ["those", "5"], 
  ["hav", "3"], 
  ["have", "3"], 
  ["haven", "3"]
]

Edited to sort by reverse frequencies.

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