rust - 您如何将文本文件中的行读入i32s元组的向量中？

Question

这是我的尝试:

use std::fs;

fn main() {
    //let input = fs::read_to_string("input.txt").unwrap();
    let input = "1, 2\n3, 4\n5, 6";
    let lines: Vec<String> = input.split("\n").map(|s| s.to_string()).collect();

    let data: Vec<(i32, i32)> = lines
        .iter()
        .map(|x| {
            x.split(',')
                .map(|y| y.trim().parse::<i32>().unwrap())
                .collect()
                .unwrap()
        })
        .collect();

    println!("{:?}", data);
}

我得到了错误:

error[E0282]: type annotations needed
  --> src/main.rs:13:18
   |
13 |                 .collect()
   |                  ^^^^^^^ cannot infer type for type parameter `B` declared on the associated function `collect`
   |
   = note: type must be known at this point
help: consider specifying the type argument in the method call
   |
13 |                 .collect::<B>()
   |                         ^^^^^

Answer 1

您无法使用.collect收集到一个元组中。一种选择是使用 Itertools::collect_tuple ，这需要itertools crate :

use itertools::Itertools;

fn main() {
    let input = "1, 2\n3, 4\n5, 6";
    let lines: Vec<String> = input.split("\n").map(|s| s.to_string()).collect();
    let data: Vec<(i32, i32)> = lines
        .iter()
        .map(|x| {
            x.split(',')
                .map(|y| y.trim().parse::<i32>().unwrap())
                .collect_tuple()
                .unwrap()
        })
        .collect();

    println!("{:?}", data);
}

Playground link