给定这个数组数组，我如何计算自身包含重复元素的数组的数量？

Question

我有一个如下所示的数组：

[[["Sports", "Soccer"], 2], [["eSports"], 1], [["Sports", "Soccer"], 3]]

在最外层数组的任何元素中，第一个元素（数组）是类别列表。第二个元素是program.id这个类别数组的来源。

因此，取上述数组中的第一个元素 - ["Sports", "Soccer"] 是 program_id: 2 的类别数组。

如何计算类别数组重复的实例？在上面的例子中，我想要的是这样的：

["Sports", "Soccer"] => Occurs 2 times, with Program Ids: 2 & 3
["eSports"] => Occurs 1 time, with Program Id: 1

我如何有效地做到这一点？

Answer 1

这个怎么样？

arr = [[["Sports", "Soccer"], 2], [["eSports"], 1], [["Sports", "Soccer"], 3]]
count = {}
arr.each do |el|
  count[el[0]] ||= []
  count[el[0]] << el[1]
end

count.each do |category, ids|
  puts "#{category} occurs #{ids.count} times, with Program Ids: #{ids.join(' & ')}"
end

输出

["Sports", "Soccer"] occurs 2 times, with Program Ids: 2 & 3
["eSports"] occurs 1 times, with Program Ids: 1

Answer 2

grouped = array.group_by { |s, id| s }.transform_values { |v| v.map(&:last) }

=> { ["Sports", "Soccer"] => [2, 3], 
     ["eSports"]          => [1] }

使用方法：

grouped.each { |k,v| 
  puts "[#{k.join(', ')}] occurs #{v.length} time(s) with ID: #{v.join(' and ')}" 
}

[Sports, Soccer] occurs 2 time(s) with ID: 2 and 3
[eSports] occurs 1 time(s) with ID: 1

给定这个数组数组，我如何计算自身包含重复元素的数组的数量？

Given this array of arrays, how do I count the number of arrays that include a duplicate element within itself?

ruby

arrays

ruby-on-rails

ruby-on-rails-6