Rust で HashMap にループで値を代入

// --------------------------------------------------------------------
/*
    hash01.rs

                        Jul/11/2020
*/
// --------------------------------------------------------------------
use std::collections::HashMap;

// --------------------------------------------------------------------
fn main(){

    eprintln! ("*** start ***");

    let mut unit_aa:HashMap <String,f64> = HashMap::new ();

    for count in 0..5 {
            let key = "key_".to_owned() + &count.to_string();
            unit_aa.insert(key, count as f64);
        }

    println!("{:?}",unit_aa);

    eprintln! ("*** end ***");
}

// --------------------------------------------------------------------

hash01: hash01.rs
    rustc hash01.rs
clean:
    rm  -f hash01

make

$ ./hash01 
*** start ***
{"key_4": 4.0, "key_0": 0.0, "key_2": 2.0, "key_1": 1.0, "key_3": 3.0}
*** end ***