在Ruby on Rails中删除数组的交替元素

Question

假设我有以下数组

可能是重复问题：
Ruby数组中的奇数（或偶数）项

假设我有以下数组

arr = ["Value0","Value1","Value2","Value3","Value4","Value5","Value6","Value7","Value8"]

我希望删除备用元素，以便我的输出数组类似于以下内容。

["Value0", "Value2", "Value4", "Value6", "Value8"]

即应该删除奇数位置上的元素。

- Salil

Answer 1

我认为这不是最快的方法，但你可以这样做。

>> arr.reject {|v| arr.index(v).odd?}
#=> ["Value0", "Value2", "Value4", "Value6", "Value8"]

或者

>> arr.each_slice(2).map(&:first)
#=> ["Value0", "Value2", "Value4", "Value6", "Value8"]

- oldergod

---

arr.each_slice(2).map(&:first) 是第二个版本的更好的实现。 - mu is too short

当然！我会更改它，谢谢。 - oldergod

Answer 2

arr.reject!.with_index{|_, i| i.odd?}

或者

arr.select!.with_index{|_, i| i.even?}

- sawa

---

不错啊。我不知道你能做到那个。 - oldergod

Answer 3

arr = ["Value0","Value1","Value2","Value3","Value4","Value5","Value6","Value7","Value8"]
flag = false
p arr.select!{flag = !flag}
#=> ["Value0", "Value2", "Value4", "Value6", "Value8"]

- steenslag

Answer 4

arr1 = arr.clone
arr.each_with_index {|el,index| arr1.delete_at(index) if index % 2 > 0 }

或者

arr1 = []
arr.each_with_index {|el,index| arr1 << el if index % 2 == 0}

- saihgala