在Ruby中返回数组的类似元素 [英] Return similar elements of array in Ruby

问题描述

说我有这样一个数组：

  arr = ['footballs_jumba_10'，'footballs_jumba_11'，'soccers_jumba_12'，
'footballs_jumba_14'，'alpha_romeo_11'，'alpha_romeo_12'，
'alpha_juliet_10'，'alpha_juliet_11'] 
  

如果我想要返回重复项（假设数组中的这些字符串中的任何一个完全相同，我只需要

  return arr.detect {| a | arr.count（a）> 1} 
  

但是，如果我只想得到数组的每个元素的前10个字符的重复项，而不是事先知道变化，那么如下：

 code> ['footballs_'，'alpha_rome'，'alpha_juli'] 
  

解决方案

这是非常简单的方法 Arry＃difference ，我提出在我的答案 here ：

  arr<< 我们添加一个只出现一次的字符串
＃=> [footballs_jumba_10，footballs_jumba_11，footballs_jumba_12，
＃footballs_jumba_14，alpha_romeo_11，alpha_romeo_12，
＃alpha_juliet_10，alpha_juliet_11，只是一次] 
 
a = arr.map {| s | s [0,10]} 
＃=> [footballs_，footballs_，footballs_，footballs_，alpha_rome，
＃alpha_rome，alpha_juli，alpha_juli，Let's add] 
b = a。差异（a.uniq）
＃=> [footballs_，footballs_，footballs_，alpha_rome，alpha_juli] 
 b.uniq 
＃=> [footballs_，alpha_rome，alpha_juli] 
  

Say I have such an array:

arr = ['footballs_jumba_10', 'footballs_jumba_11', 'footballs_jumba_12',
       'footballs_jumba_14', 'alpha_romeo_11', 'alpha_romeo_12',
       'alpha_juliet_10', 'alpha_juliet_11']

If I wanted to return duplicates, (assuming any of these strings in the array were exactly identical, I would just

return arr.detect{ |a| arr.count(a) > 1 }

but, what if I wanted to get only duplicates of the first 10 characters of each element of the array, without knowing the variations beforehand? Like this:

['footballs_', 'alpha_rome', 'alpha_juli']

解决方案

This is quite straightforward with the method Arry#difference that I proposed in my answer here:

arr << "Let's add a string that appears just once"
  #=> ["footballs_jumba_10", "footballs_jumba_11", "footballs_jumba_12",
  #    "footballs_jumba_14", "alpha_romeo_11", "alpha_romeo_12",
  #    "alpha_juliet_10", "alpha_juliet_11", "Let's add a string that appears just once"]

a = arr.map { |s| s[0,10] }
  #=> ["footballs_", "footballs_", "footballs_", "footballs_", "alpha_rome",
  #    "alpha_rome", "alpha_juli", "alpha_juli", "Let's add "] 
b = a.difference(a.uniq)
  #=> ["footballs_", "footballs_", "footballs_", "alpha_rome", "alpha_juli"] 
b.uniq
  #=> ["footballs_", "alpha_rome", "alpha_juli"] 

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