for-loop - 如何在循环内创建向量的向量？

Question

我正在尝试使用for循环创建向量的向量。我尝试了以下设计，但没有成功:

// num_partitions is the primary vector, v is vector that contains a set of integers
// This function should return a Primary Vector that hold num_partitions of vectors

fn partition_data(num_partitions: usize, v: &Vec<usize>) -> Vec<Vec<usize>> {
    let partition_size = v.len() / num_partitions;

    // Create a vector that will contain vectors of integers
    let mut xs: Vec<Vec<usize>> = Vec::new();
 
    for j in 0..partition_size {
        for i in 0..partition_size {
            // create a new Vector and push elements to it
            let mut x1: Vec<usize> = Vec::new();
            x1.push(v[i]);
        }
        // push this new Vector the the Primary Vector
        xs.push(x1);
    }
   
    // return primary vector
    xs
}

Answer 1

Rust标准库中有一些方便的函数，它们已经完成了仅使用Iterators即可轻松实现此函数所需的大部分工作:

fn partition_data(num_partitions: usize, v: &Vec<usize>) -> Vec<Vec<usize>> {
    let partition_size = v.len() / num_partitions;
    v.chunks(partition_size)
        .map(|chunk| chunk.to_vec())
        .collect()
}

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