Ruby Hash - 按值和打印键排序

Question

This is my hash.

=> {"f11"=>1, "f12"=>3, "f13"=>3, "f07"=>5, "f10"=>1}

I'd like to sort by the values largest to smallest and then make an array out of the keys.

=> ["f07", "f12", "f13", "f11", "f10"]

Answer 1

Here's a one-liner for you (I love ruby!):

h.keys.sort {|a, b| h[b] <=> h[a]}

Hope that helps!

Answer 2

Hash has the Enumerable module mixed in which provides us with methods like sort and sort_by.In this situation we can use sort_by to get a collection by order of values.

 h={"f11"=>1, "f12"=>3, "f13"=>3, "f07"=>5, "f10"=>1} 
 h.sort_by{ |key, value| -value }  
 => [["f07", 5], ["f12", 3], ["f13", 3], ["f11", 1], ["f10", 1]]

Answer 3

更短！：

h.keys.sort_by{|a| h[a]}.reverse

Answer 4

a = {"f11"=>1, "f12"=>3, "f13"=>3, "f07"=>5, "f10"=>1}
b = Hash[a.sort_by{|k,v| v}]
puts b.keys.reverse