在ruby中使用sort_by（用于rails）？

So I've built a custom array of users like such:

所以我构建了一个自定义的用户数组，如：

[["user1",432],["user1",53],["user9",58],["user5",75],["user3",62]]

I want to sort them by the 2n'd value in each array, from largest to smallest. I have a feeling using sort or sort_by for arrays is the way to do this, but I'm not really sure how to accomplish it

我想按每个数组中的2n'd值对它们进行排序，从最大到最小。我有一种感觉，使用sort或sort_by进行数组是这样做的方法，但我不确定如何实现它

3 个解决方案

#1

sort_by

If you're interested in sort_by, you could destructure your inner arrays

如果您对sort_by感兴趣，可以对内部数组进行解构

array.sort_by { |_, x| x }.reverse

or call the index operator

或者调用索引运算符

array.sort_by { |x| x[1] }.reverse

Instead of reversing you could negate values returned from the block.

而不是反转你可以否定从块返回的值。

array.sort_by { |_, x| -x }
array.sort_by { |x| -x[1] }

Yet another alternative would be to use an ampersand and Array#last.

另一个替代方案是使用＆符号和数组#last。

array.sort_by(&:last).reverse

sort

A solution using sort could be

使用sort的解决方案可能是

array.sort { |x, y| y[1] <=> x[1] }

#2

use this: array.sort_by { |a| -a[1] }

使用它：array.sort_by {| a | -a [1]}

#3

One more solution to sort_by in reverse (- doesn't work in all cases, think sorting by string):

反向排序的另一个解决方案（ - 在所有情况下都不起作用，考虑按字符串排序）：

class Invertible
  include Comparable
  attr_reader :x

  def initialize(x)
    @x = x
  end

  def <=> (x)
    x.x <=> @x
  end
end

class Object
  def invertible
    Invertible.new(self)
  end
end

[1, 2, 3].sort_by(&:invertible) #=> [3, 2, 1]
["a", "b", "c"].sort_by(&:invertible) #=> ["c", "b", "a"]

It is slower than reverse in simple case, but may work better with complex sorts:

在简单的情况下，它比反向慢，但对于复杂的排序可能会更好：

objs.sort_by do |obj|  
  [obj.name, obj.date.invertible, obj.score, ...]
end