rust - Is there a fast way to check a Vec for an error result? -

i'm using rayon iterate on vector, producing vec of results:

let coordinates = &[[38.5, -120.2], [40.7, -120.95], [430.252, -126.453]] let mut res = vec![]; coordinates     .par_iter()     .map(|pair| {         match (check(&pair[0]), check(&pair[1])) {             (ok(v1), ok(v2)) => ok([v1, v2]),             (err(v), _) => err(v),             (_, err(v)) => err(v),         }     })     .collect_into(&mut res); 

i'd check res error values, convert them string , return them using try!()

this works, it's slow , inefficient, considering i'm allocating new vector aggregate results or pull out error:

let errcheck: result<vec<_>, f64> = res.iter().map(|elem| *elem).collect(); try!(errcheck.map_err(|e| format!("error: {}", e).to_string())); 

this problem appears rayon-specific; if use .iter(), can collect directly errcheck using collect() , map_err() in match arms, can't seem using par_iter().

is there better way it?

if need items not fulfil conditions, there filter():

let bounds1 = (-90.0, 90.0); let bounds2 = (-180.0, 180.0); let (xmin, xmax) = bounds1; let (ymin, ymax) = bounds2;  coordinates.par_iter().filter(|pair| {     let x = pair[0];     let y = pair[1];     !((xmin <= x) && (x <= xmax) && (ymin <= y) && (y <= ymax)) }).for_each(|pair| {     println!("bad pair: {} {}", pair[0], pair[1]); }); 

in other words, map right operation in first place.