ruby - 如何根据 Ruby 中的键值对之一按降序对散列的行进行排序？

Question

我有以下哈希：

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“b”按降序对哈希进行排序，以便最终得到：

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}

实现这一目标的最佳方法是什么？Ruby 中有没有一种方法可以为您做到这一点？

Answer 1

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

Answer 2

您似乎有一种特殊情况，其中行不是数组而是哈希，因此您希望根据值的顺序为每个键重新分配值，首先从哈希中创建数组，对其进行排序，然后根据新索引，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]]}]

输出是：

{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}}

也就是说，为什么行是哈希？它可以更好地用一个数组来表示

Answer 3

你可以做

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