ruby - Ruby 中的 MapReduce 数组

Question

我有两个这样的数组:

["1","7","8","10"]

和

["1","2","3","6","9","11"]

这些数组表示来自用户选择的名为 Place 的类的 ID。我想选择得票最多的地点 ID。我尝试了 transpose 但由于数组的大小不同，因此无法进行转置。

这个例子的预期输出是:

{ "1" => 2, "7" => 1, "8" => 1, "10" => 1, "2" => 1, "3" => 1, "6" => 1, "9" => 1, "11" => 1 }

Answer 1

您可以连接所有数组并计算相同元素的数量，如下所示:

arrays = [["1","7","8","10"], ["1","2","3","6","9","11"]].reduce(:+)
arrays.inject(Hash.new(0)) { |memo, e| memo.update(e => memo[e] + 1) }
# "{ "1" => 2, "7" => 1, "8" => 1, "10" => 1, "2" => 1, "3" => 1, "6" => 1, "9" => 1, "11" => 1 }"

一旦你得到这个中间结果，使用 max_by 从散列中选择具有最大值的键:

arrays = [["1","7","8","10"], ["1","2","3","6","9","11"]].reduce(:+)
arrays.inject(Hash.new(0)) { |memo, e| memo.update(e => memo[e] + 1) }
      .max_by { |_, count| count }[0]
#=> "1"