如何根據Ruby中的鍵值對之一對哈希行進行降序排序？

Question

我有以下哈希值：

lines[0] = {"a" => dog, "b" => 32, "c" =>555, "d" => 100}
lines[1] = {"a" => cat, "b" => 34, "c" =>554, "d" => 4542}
lines[2] = {"a" => bird, "b" => 31, "c" =>532435, "d" => 23}

我想按降序以“ b”對哈希進行排序，以便最終得到：

lines[0] = {"a" => cat, "b" => 34, "c" =>554, "d" => 4542}
lines[1] = {"a" => dog, "b" => 32, "c" =>555, "d" => 100}
lines[2] = {"a" => bird, "b" => 31, "c" =>532435, "d" => 23}

實現這一目標的最佳方法是什么？ Ruby中有沒有一種方法可以幫助您？

Answer 1

lines.sort_by! {|hash| -hash["b"]}

Answer 2

您似乎有一個特殊的情況，即line不是數組而是Hash，因此您想根據值的順序為每個鍵重新分配值，首先要從Hash中創建數組，然后對其進行排序，然后根據Hash創建一個Hash。新索引，例如

lines = {}
lines[0] = {"a" => :dog, "b" => 32, "c" =>555, "d" => 100}
lines[1] = {"a" => :cat, "b" => 34, "c" =>554, "d" => 4542}
lines[2] = {"a" => :bird, "b" => 31, "c" =>532435, "d" => 23}

require 'pp'
pp Hash[lines.map.sort_by {|k,v| -v["b"]}.map.with_index {|v, index| [index, v[1]]}]

輸出為：

{0=>{"a"=>:cat, "b"=>34, "c"=>554, "d"=>4542},
 1=>{"a"=>:dog, "b"=>32, "c"=>555, "d"=>100},
 2=>{"a"=>:bird, "b"=>31, "c"=>532435, "d"=>23}}

也就是說，為什么行是哈希？ 最好用數組表示

Answer 3

你可以做

lines.sort! { |a, b| b["b"] <=> a["b"] }