ruby - 如何获取数组中相同元素出现的索引数组

Question

输入:[1,2,2,3,4,2]

输出:2 = [1,2,5] 的索引

Answer 1

这样的方法:

def indexes_of_occurrence(ary, occ)
  indexes = []
  ary.each_with_index do |item, i|
    if item == occ
      indexes << i
    end
  end
  return indexes
end

为您提供以下内容:

irb(main):048:0> indexes_for_occurrence(a, 2)
=> [1, 2, 5]
irb(main):049:0> indexes_for_occurrence(a, 1)
=> [0]
irb(main):050:0> indexes_for_occurrence(a, 7)
=> []

我敢肯定有一种方法可以做到单行(似乎总是有!)，但这就可以了。