How to Sort Vector of Structs by Chronos DateTime Field?-CodePudding

I have this struct

pub struct Items {
    pub symbol: String,
    pub price: f64,
    pub date: DateTime<Utc>,
}

I have a vector of these structs. I would like to sort them by date. How would I go about doing that? I tried deriving PartialEq, Ord, Eq, etc... but Rust complains about the float fields.

CodePudding user response：

The easiest way is to use one of the provides sort functions implemented for Vec like sort_by, sort_by_key, or sort_by_key_cached.

// Using sort_by
foo_items.sort_by(|a, b| a.date.cmp(&b.date));

// Using sort_by_key
foo_items.sort_by_key(|x| x.date);

// Using sort_by_key_cached (Faster if key is very large)
foo_items.sort_by_cached_key(|x| x.date);

And don't forget you always have the option to manually implement traits that are normally derived.

use std::cmp::Ordering;

impl PartialEq for Items {
    fn eq(&self, other: &Self) -> bool {
        // idk what symbol is, but use it anyway
        self.symbol == other.symbol && self.date == other.date
    }
}

impl Eq for Items {}

impl PartialOrd for Items {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.date.partial_cmp(&other.date)
    }
}

impl Ord for Items {
    fn cmp(&self, other: &Self) -> Ordering {
        self.date.cmp(&other.date)
    }
}

CodePudding user response：

#[derive(Debug)]
pub struct S {
    pub s: f64,
    
}


fn main() {
    let mut v = vec![S{s:0.3}, S{s:1.3}, S{s:7.3}]; 

    v.sort_by(|a, b| a.s.partial_cmp(&b.s).unwrap());

    println!("{:#?}",v);
}