Function nice 

pub fn nice(start: f64, stop: f64, count: usize) -> (f64, f64)

Extend the domain to nice round values.

Returns (nice_start, nice_stop) that encompass the original domain and align with the tick step.

Example

use d3rs::array::nice;

let (start, stop) = nice(0.134, 0.867, 5);
assert!(start <= 0.134);
assert!(stop >= 0.867);