Crate min_max

min-max: max! and min! macros for Rust

Why?

Sometimes you want to find the maximum of a bunch of scalars. Usually you would write something like max(x1, max(x2, max(x3, x4))). The max! macro provided by this crate simplifies that to max!(x1, x2, x3, x4). (Note, for an iterable data structure, you would use xx.iter().max()).

Usage

Add this to your Cargo.toml:

min-max = "0.1"

Then, for example:

use min_max::*;

fn main() {
    let max = max!(1, 5, 7, 2, 4, 9, 3);
    assert_eq!(max, 9);
    let min = min!(1, 5, 7, 2, 4, 9, 3);
    assert_eq!(min, 1);
    let min_max = min_max!(1, 5, 7, 2, 4, 9, 3);
    assert_eq!(min_max, (min, max));
}

Does it work on floats?

Yep. But you need to use max_partial!/min_partial!

use min_max::*;

fn main() {
    let partial_max = max_partial!(1.8f64, 5.8, 7.8, 2.8, 4.8, 9.8, 3.8);
    assert!((9.8 - partial_max).abs() < 1e-5);
    let partial_min = min_partial!(1.8f64, 5.8, 7.8, 2.8, 4.8, 9.8, 3.8);
    assert!((1.8 - partial_min).abs() < 1e-5);
}

What about NaN?

Do not use when your data contains NaN. When NaN is at the end, NaN is returned. Otherwise, the min/max excluding NaN is returned.

use min_max::*;

fn main() {
    let partial_max = max_partial!(1.8, 5.8, f64::NAN, 2.8, 4.8, 9.8, 3.8);
    assert!((9.8 - partial_max).abs() < 1e-5);
    let partial_max = max_partial!(1.8, 5.8, 2.8, 4.8, 9.8, 3.8, f64::NAN);
    assert!(partial_max.is_nan());
    let partial_min = min_partial!(1.8, 5.8, f64::NAN, 2.8, 4.8, 9.8, 3.8);
    assert!((1.8 - partial_min).abs() < 1e-5);
    let partial_min = max_partial!(1.8, 5.8, 2.8, 4.8, 9.8, 3.8, f64::NAN);
    assert!(partial_min.is_nan());
}

Can I use custom types?

Sure, why not?

use min_max::*;

#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Clone, Copy)]
struct Point {
    x: u16,
    y: u16,
}

fn main() {
    let a = Point { x: 5, y: 8 };
    let b = Point { x: 10, y: 92 };
    let c = Point { x: 0, y: 3 };
    let max = max!(a, b, c);
    assert_eq!(max, b);
}

What’s going on under the hood?

Well, max!(x1, x2, x3) expands to:

std::cmp::max(x1, std::cmp::max(x2, std::cmp::max(x3)))

and so on. min! works similarly, but with std::cmp::min.

min_partial! and max_partial uses the min and max functions from the partial-min-max crate.

Macros

max

Returns the maximum element of the arguments.

max_partial

Returns the maximum element of the arguments. Uses partial_min_max::max for comparison.

min

Returns the minimum element of the arguments.

min_max

Returns the minimum and maximum element of the arguments.

min_max_partial

Returns the minimum and maximum element of the arguments. Uses partial_min_max::min for comparison.

min_partial

Returns the maximum element of the arguments. Uses partial_min_max::min for comparison.

Functions

max

A version of std::cmp::max that works with PartialOrd types.

min

A version of std::cmp::min that works with PartialOrd types.