红宝石阵列 - 反向迭代和下一元素之前 [英] Ruby Array - reverse iterate with next and before element

问题描述

如何扭转遍历数组旁边和当前元素的元素前？

How to reverse iterate an Array with next and before element of the current element ?

时有可能使用 each_cons 与 reverse_each ？

推荐答案

是的，这是可能的。

[1,2,3,4,5,6].reverse_each.each_cons(3) { |before, current, next_|
  p [before, current, next_]
}

打印

[6, 5, 4]
[5, 4, 3]
[4, 3, 2]
[3, 2, 1]

---

([nil]+[1,2,3,4,5,6]+[nil]).reverse_each.each_cons(3) { |before, current, next_|
  p [before, current, next_]
}

打印

[nil, 6, 5]
[6, 5, 4]
[5, 4, 3]
[4, 3, 2]
[3, 2, 1]
[2, 1, nil]

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