Question

我正在寻找一种方法来检测数组中的以下值是否重复，如果是，则删除它。它应该适用于字符串和整数。

例如，给定数组：

arr = ["A", "B", "B", "C", "c", "A", "D", "D"]

返回：

arr = ["A", "B", "C", "c", "A", "D"]

我尝试创建一个空数组a，然后铲除值，提供以下值不等于当前值。我试着这样做：

arr.each do |x|
  following_value = arr.index(x) + 1
  a << x unless x == arr[following_value]
end

不幸的是，它没有将重复值中的一个铲入数组中，而是没有铲除。

arr = ["A", "C", "c", "A"]

有人可以帮忙吗？奖励积分告诉我我的方法究竟出了什么问题。

谢谢！

Answer 1

首先，这里是更简单的解决方案：

> arr.delete_if.with_index { |e, ind| e == arr[ind+1] }
#=> ["A", "B", "C", "c", "A", "D"]

但是，这个解决方案会改变arr。以下是没有变异的单行解决方案：

arr.each_with_index.with_object([]) { |(e, ind), res| res << e if e != arr[ind+1] }
arr.each_with_object([]) { |e, res| res << e if res.last != e }

您的问题在这一行：a << x unless x == arr[following_value] 您说：如果element不等于result，请将next element放入arr.each do |x| a << x unless a.last == x end。所以，相反，您可以这样说：如果结果的最后一个元素不等于，则将此元素置于结果中：

&varlist. = OriginCd,DestinCd

Answer 2

我会使用select，所以你可以这样做：

a = ["A", "B", "B", "C", "c", "A", "D", "D"]

# without mutation
b = a.select.with_index { |e, i| a[i+1] != e }
a #=> ["A", "B", "B", "C", "c", "A", "D", "D"]
b #=> ["A", "B", "C", "c", "A", "D"]

# with mutation
a.select!.with_index { |e, i| a[i+1] != e }
a #=> ["A", "B", "C", "c", "A", "D"]

BTW您的方法无效，因为arr.index(x) returns index of first object for which block is true：

arr = ["A", "B", "B", "C", "c", "A", "D", "D"]
arr.each do |x|
  puts "#{x} has index #{arr.index(x)}"
end
A has index 0
B has index 1
B has index 1 # you were expecting 2
C has index 3
c has index 4
A has index 0 # you were expecting 5
D has index 6
D has index 6 # you were expecting 7

Answer 3

这是一个简洁的选择：

arr = ["A", "B", "B", "C", "c", "A", "D", "D"]

arr.chunk(&:itself).map(&:first)
# => ["A", "B", "C", "c", "A", "D"]

在repl.it上查看：https://repl.it/JGV4/1

Answer 4

来自this的Cary Swoveland回答：

def remove_consecs ar
  enum = ar.each
  loop.with_object([]) do |_, arr|
    curr = enum.next
    nxt = arr.last || enum.peek
    arr << curr if curr != nxt
  end
end

remove_consecs ["A", "B", "B", 'D', "C", "c", "A", "D", "D"]
#=> ["A", "B", "D", "C", "c", "A", "D"]

检测数组中的以下值是否重复

4 个答案: