Ruby Arrays: keep repeated values only from the end of an array of arrays
如果我有一个数组：
1 | [[1,"foo"], [2,"bar"], [3,"foo"], [4,"foo"], [5,"bar"], [6,"baz"]] |
如何消除重复值，使其保持在数组末尾，从而导致：
1 | [[4,"foo"], [5,"bar"], [6,"baz"]] |
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谢谢！
我尝试过很多方法，比如按照荒谬的路线，但都没有成功。
1 2 3 | a.delete_if {|q| q if q[1] in a} # syntax error a.each {|q| q.shift if q[1] in a[q][1]} # syntax error |
还有更多。…
应该这样做：
1 2 | a.reverse.uniq(&:last).reverse => [[4,"foo"], [5,"bar"], [6,"baz"]] |
1 | arr.group_by{|x|x[1]}.values.map(&:last) |
。
它也可以通过使用Ruby的
A Hash is a dictionary-like collection of unique keys and their values. Also called associative arrays,....
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1 2 3 | array = [[1,"foo"], [2,"bar"], [3,"foo"], [4,"foo"], [5,"bar"], [6,"baz"]] Hash[array].invert.map { |k,v| [v,k] } # => [[4,"foo"], [5,"bar"], [6,"baz"]] |
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按@uri建议更新-
1 | Hash[array].invert.invert.to_a |