vector - How can I take an item from a Vec in Rust? -

what want method this:

fn take<t>(vec: vec<t>, index: usize) -> option<t> 

however, can't find such method. missing something? or there reason unsafe / can't done correctly.

edit: different question built in *safe* way move out of vec<t>? there goal remove method didn't panic on out of bounds access (that instead returned result.) here i'm looking method consumes vec, , returns 1 of elements. none of answers above question address question.

edit 2: clarify further, i'm looking method consumes vec , returns 1 element, without overhead of restoring vec's invariants way remove , swap_remove do.

you can write function this:

fn take<t>(mut vec: vec<t>, index: usize) -> option<t> {     if vec.get(index).is_none() {         none     } else {         some(vec.swap_remove(index))     } } 

this guaranteed o(1).

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to mention solution using iterators:

fn take<t>(vec: vec<t>, index: usize) -> option<t> {     vec.into_iter().nth(index) } 

i write this:

while iterator::nth() linear time operation, iterator on vector overrides method make o(1) operation.

but noticed, true iterator iterates on slices. std::vec::intoiter iterator used in code above, doesn't override nth(). has been attempted here, doesn't seem easy.

so: of right now, code above o(n) operation!

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