sorting - 如何对带有 map 状闭包的Rust Vector进行排序？

Question

我想使用某种类似于闭包的格式对结构的Vector进行排序。这就是我的想法:

struct PointTracker {
    positive: u32,
    negative: u32,
}

// ....

fn main() {
    let item: Vec<PointTracker> // ....

    // e.g: [{positive: 3, negative: 4}, {positive: 5, negative: 0}, {positive: 2, negative: 10}]
    
    let sorted_item = item
        .iter()
        .sort_with(|x: PointTracker| x.positive - x.negative)
        .collect::<PointTracker>();

    // sorted from greatest to least:
    // [{positive: 5, negative: 0}, {positive: 3, negative: 4}, {positive:2, negative: 10}]
}

我在寻找的是某种函数，例如上面的函数，该函数根据闭包中返回的值对项目进行排序。这将取正值，从中减去负值，然后返回结果。第一个未排序项的总和为: [-1, 5, -8]，而已排序项的总和为(如预期的那样): [5, -1, -8]此功能是否有某种包装箱，或者如果该包装箱不存在，我应该自己编写吗？

Answer 1

您要搜索的函数是sort_by_key:

#[derive(Debug)]
struct PointTracker {
    positive: u32,
    negative: u32,
}

fn main() {
    let mut item = vec![
        PointTracker {
            positive: 3,
            negative: 4,
        },
        PointTracker {
            positive: 5,
            negative: 0,
        },
        PointTracker {
            positive: 2,
            negative: 10,
        },
    ];

    item.sort_by_key(|x| x.positive as i32 - x.negative as i32);

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

输出:

[
    PointTracker {
        positive: 2,
        negative: 10,
    },
    PointTracker {
        positive: 3,
        negative: 4,
    },
    PointTracker {
        positive: 5,
        negative: 0,
    },
]