计算数组中的更改 [英] Counting changes in an array

问题描述

我想计算数组中红色 后跟绿色 的次数：

I would like to count the number of times "red" is followed by "green" in this array:

["red", "orange", "green", "red", "yellow", "blue", "green"]

如果是另一种颜色，代码应忽略它并继续进行下一项

If it is another color, the code should ignore it and proceed to the next item in the array.

event_type.each_slice(2) do |red, green|
  break unless green
  count = count + 1
end

p "The count is #{count}"

步骤1：

Look for red

步骤2：

IF not last item 
           Compare with next item on array
ELSE       Go to Step 4

步骤3：

IF green, count = count + 1
          Go to Step 1
ELSE      Go to Step 2

步骤4：

Print Count

推荐答案

以下是我认为的解决方案。当然，还有更多的重构空间，您可以从这里开始。

Below one is solution I believe. Sure there is more room to refactor it, you can start from here.

a = ["red", "orange", "green", "red", "yellow", "blue", "green"]    
a.reject {|e| !['red', 'green'].include? e }
  .each_cons(2)
  .select{|e| e == ['red', 'green']}
  .size

A更多艺术版本。

def neither_red_nor_green e
  !['red', 'green'].include? e
end

def red_followed_by_green ary
  ary == ['red', 'green']
end

a.reject(&method(:neither_red_nor_green))
  .each_cons(2)
  .select(&method(:red_followed_by_green))
  .size

更新

感谢@Stefan提供以下建议。

Thanks to @Stefan for below suggestions.

def either_red_or_green e
  ['red', 'green'].include? e
end

def red_followed_by_green ary
  ary == ['red', 'green']
end


a.select(&method(:either_red_or_green))
  .each_cons(2)
  .count(&method(:red_followed_by_green))

更新

按照Stefan Pochmann的建议，

As Stefan Pochmann proposed,

a.select(&method(:either_red_or_green))
  .each_cons(2)
  .count(['red', 'green'])

将完成相同的工作，而无需调用其他方法。

will do the same work, without needing another method call.

这篇关于计算数组中的更改的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！