英文:
Flatten a set of pairs in Rust
问题
我正在使用Rust中的HashSet<(usize, usize)>处理整数对的集合，我的目标是计算一个包含这些整数对中出现的所有节点的HashSet<usize>。从本质上讲，这是一个“展平”操作。
假设变量set: HashSet<(usize, usize)>包含初始的整数对集合。我首次尝试计算展平版本如下：
let res: HashSet<usize> = set.iter().flatten().collect()
然而，我遇到了错误：“&(usize, usize)不是一个迭代器，Iterator特质未实现于&(usize, usize)，&(usize, usize)需要实现IntoIterator特质以满足flatten中的要求。”。
我认为问题在于迭代器是对引用的，所以我也尝试使用into_iter，但我收到了相同的错误消息，这次是说“(usize, usize)不是一个迭代器...”。
我确实有一段代码，使用for循环和push操作可以正常工作，但我希望以更函数式的方式使用flatten来完成。
英文:
I am working with sets of pairs of integers in Rust using HashSet<(usize, usize)>, and my goal is to compute a set HashSet<usize> which contain all nodes appearing in those pairs. Essentially, this is a flatten operation.
Let's suppose variable set: HashSet<(usize, usize)> contains the initial set of pairs. My first attempt to compute the flattened version was:
let res: HashSet<usize> = set.iter().flatten().collect()
however I encounter the error: "&(usize, usize) is not an iterator the trait Iterator is not implemented for &(usize, usize) required for &(usize, usize) to implement IntoIterator. Required by a bound in flatten."
I thought the issue was that the iterator was over references so I also tried using into_iter instead, but I get the same error message, this time saying "(usize, usize) is not an iterator..."
I do have a piece of code that works fine using a for loop and the push operation, but I would like to do it in a more functional way with flatten.
答案1
得分: 3
将元组简单地转换为一个可迭代的数组：
let res: HashSet<usize> = set.iter().flat_map(|&(a, b)| [a, b]).collect();
英文:
Simply convert the tuple to an array, which is iterable:
let res: HashSet<usize> = set.iter().flat_map(|&(a, b)| [a, b]).collect();
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