返回红宝石阵类似的元素 [英] Return similar elements of array in Ruby

问题描述

说我有这样的一个数组：

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

如果我想回到副本，（假设任何数组中的这些字符串是完全相同的，我只想

 收益arr.detect {| A | arr.count（a）及GT; 1}
 

但是，如果我想获得数组的每个元素的前10个字符的唯一副本，不知道事先的变化是什么？像这样的：

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

解决方案

这是该方法很简单哈利＃区别我在我的答案的here ：

 改编＆LT;＆LT; 让我们添加一个字符串出现只是一次
  ＃=＆GT; [footballs_jumba_10，footballs_jumba_11，footballs_jumba_12，
  ＃footballs_jumba_14，alpha_romeo_11，alpha_romeo_12，
  ＃alpha_juliet_10，alpha_juliet_11，让我们补充说，只是出现一个字符串一次]A = {arr.map | S | S [0,10]}
  ＃=＆GT; [footballs_，footballs_，footballs_，footballs_，alpha_rome，
  ＃alpha_rome，alpha_juli，alpha_juli，让我们增加]
B = a.difference（a.uniq）
  ＃=＆GT; [footballs_，footballs_，footballs_，alpha_rome，alpha_juli]
b.uniq
  ＃=＆GT; [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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