参数阵列＃uniq的（即，uniq_by） [英] Parameterized Array#uniq (i.e., uniq_by)

问题描述

如果不是从一个数组删除重复的元素，我想删除有一个共同的特定属性的元素是什么？

What if instead of removing duplicate elements from an array, I want to remove elements that have a specific property in common?

具体来说，我想从数组中删除所有的字符串重复的精华，其中的本质是这样定义的：

Specifically, I want to remove all strings from an array with duplicate "essences", where essence is defined like this:

class String
  def essence
    downcase.gsub('&', 'and').gsub(/[^a-z0-9]/, '')
  end
end

我想是这样的：

['a', 'A', 'b'].uniq_by(&:essence)
# => ['a', 'b'] (or ['A', 'b']; I don't really care)

什么是实现这一目标的最佳方式？

What's the best way to accomplish this?

推荐答案

的ActiveSupport有阵列＃uniq_by 的，这是code：

Activesupport has a Array#uniq_by, and this is the code:

class Array
  def uniq_by
    hash, array = {}, []
    each { |i| hash[yield(i)] ||= (array << i) }
    array
  end
end

刻面也有一个可枚举＃uniq_by

module Enumerable    
  def uniq_by
    h = {}
    inject([]) {|a,x| h[yield(x)] ||= a << x}
  end    
end

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