红宝石:如何找到数组中的非唯一元素并用出现次数打印每个元素? [英] ruby: how to find non-unique elements in array and print each with number of occurrences?

问题描述

我有

a = ["a", "d", "c", "b", "b", "c", "c"]

，并且需要打印类似的内容(按出现的次数降序排列):

and need to print something like (sorted descending by number of occurrences):

c:3
b:2

我了解第一部分(发现不唯一)是:

I understand first part (finding NON-unique) is:

b = a.select{ |e| a.count(e) > 1 }
=> ["c", "b", "b", "c", "c"] 

或

puts b.select{|e, c| [e, a.count(e)] }.uniq

c
b

如何输出出现次数倒退的每个非唯一变量?

How to output each non-unique with number of occurrences sorted backwards?

推荐答案

puts a.uniq.
       map { | e | [a.count(e), e] }.
       select { | c, _ | c > 1 }.
       sort.reverse.
       map { | c, e | "#{e}:#{c}" }

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