检测数组中的下列值是否为重复值
检测数组中的下列值是否为重复值
提问于 2017-06-28 20:24:04
我希望创建一个方法来检测数组中的以下值是否是重复的，如果是的话，将其删除。它应该同时适用于字符串和整数。
例如，给定Array：
arr = ["A", "B", "B", "C", "c", "A", "D", "D"]返回：
arr = ["A", "B", "C", "c", "A", "D"]我尝试创建一个空的数组a，并在其中铲入值，提供以下值与当前值不相等。我尝试过这样做：
arr.each do |x|
following_value = arr.index(x) + 1
a << x unless x == arr[following_value]
end不幸的是，它没有将一个重复的值铲入数组中，而是两者都不铲。
arr = ["A", "C", "c", "A"] 有人能帮忙吗？告诉我我的方法到底出了什么问题。
谢谢!
回答 4
Stack Overflow用户
回答已采纳
发布于 2017-06-28 20:31:59
首先，这里有更简单的解决方案：
> arr.delete_if.with_index { |e, ind| e == arr[ind+1] }
#=> ["A", "B", "C", "c", "A", "D"]但是，这个解决方案将改变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 }您在这一行中的问题：a << x unless x == arr[following_value]，您说:如果element与next element不相等，则将其放入result中。因此，您可以这样说:如果结果的最后一个元素与其不相等，则将此元素放到结果中
arr.each do |x|
a << x unless a.last == x
endStack Overflow用户
发布于 2017-06-28 21:04:19
我会使用选择，这样你就可以做如下的事情：
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"]顺便说一句，您的方法不起作用，因为arr.index(x) 返回块为真的第一个对象的索引。
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 7Stack Overflow用户
发布于 2017-06-28 22:05:55
这里有一个简洁的替代方案：
arr = ["A", "B", "B", "C", "c", "A", "D", "D"]
arr.chunk(&:itself).map(&:first)
# => ["A", "B", "C", "c", "A", "D"]在repl.it：https://repl.it/JGV4/1上看到它
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/44811928
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