How to sort a Ruby Hash by number value?
RubyHashRuby Problem Overview
I have a counter hash that I am trying to sort by count. The problem I am running into is that the default Hash.sort function sorts numbers like strings rather than by number size.
i.e. Given Hash:
metrics = {"sitea.com" => 745, "siteb.com" => 9, "sitec.com" => 10 }
Running this code:
metrics.sort {|a1,a2| a2[1]<=>a1[1]}
will return a sorted array:
[ 'siteb.com', 9, 'sitea.com', 745, 'sitec.com', 10]
Even though 745 is a larger number than 9, 9 will appear first in the list. When trying to show who has the top count, this is making my life difficult. :)
Any ideas on how to sort a hash (or an array even) by number value size?
I appreciate any help.
Ruby Solutions
Solution 1 - Ruby
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}
Solution 2 - Ruby
Since value is the last entry, you can do:
metrics.sort_by(&:last)
Solution 3 - Ruby
Already answered but still. Change your code to:
metrics.sort {|a1,a2| a2[1].to_i <=> a1[1].to_i }
Converted to strings along the way or not, this will do the job.
Solution 4 - Ruby
That's not the behavior I'm seeing:
irb(main):001:0> metrics = {"sitea.com" => 745, "siteb.com" => 9, "sitec.com" =>
10 }
=> {"siteb.com"=>9, "sitec.com"=>10, "sitea.com"=>745}
irb(main):002:0> metrics.sort {|a1,a2| a2[1]<=>a1[1]}
=> [["sitea.com", 745], ["sitec.com", 10], ["siteb.com", 9]]
Is it possible that somewhere along the line your numbers are being converted to strings? Is there more code you're not posting?