Look up key in HashMap<(String, usize), f64> in Rust [duplicate]

Question

I have a HashMap<(String, usize), f64>. I also have a &str and a usize, which I would like to look up in this HashMap without cloning. Is there a way to lookup a (&str, usize) as a (String, usize) somehow?

Answer 1

No, you can't. The options for looking up in the HashMap<K,V> are:

• The entry method, which requires a K by value, which in your case is a (String, usize) - so you'd need to construct a String.
• The various get, contains_key etc. all take a "borrowed" form of K (the documentation says &Q, where K: Borrow<Q>; this means either a &(String, usize) or something that can produced one.

Technically you could iterate through it and do your own comparisons, but that's probably not what you want!