Iterator Pipelines

Filter, Map, Collect

Transform Matching Items

Iterator pipelines can filter values, transform the survivors, and collect the final sequence.

Program

Play the program to choose the minimum value that passes through the pipeline.

min
filter_map_collect.rs
Replay: real traced execution (multi-file project)
fn main() {
    let min = 4;
    let values = [1, 3, 4, 6, 8];
    let doubled: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();
    println!("{:?}", doubled);
}

fn main() {
    let min = 2;
    let values = [1, 3, 4, 6, 8];
    let doubled: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();
    println!("{:?}", doubled);
}

fn main() {
    let min = 6;
    let values = [1, 3, 4, 6, 8];
    let doubled: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();
    println!("{:?}", doubled);
}

  1. min ← 4, values ← [1, 3, 4, 6, 8], doubled ← [8, 12, 16]

    1fn main() {2    let mi→ 4n = 4; //@min=4, 2, 63    let value→ [1, 3, 4, 6, 8]s = [1, 3, 4, 6, 8];4    let double→ [8, 12, 16]d: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();5    println!("{:?}", doubled);6}
    output[8, 12, 16]

  1. min ← 2, values ← [1, 3, 4, 6, 8], doubled ← [6, 8, 12, 16]

    1fn main() {2    let mi→ 2n = 2;3    let value→ [1, 3, 4, 6, 8]s = [1, 3, 4, 6, 8];4    let double→ [6, 8, 12, 16]d: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();5    println!("{:?}", doubled);6}
    output[6, 8, 12, 16]

  1. min ← 6, values ← [1, 3, 4, 6, 8], doubled ← [12, 16]

    1fn main() {2    let mi→ 6n = 6;3    let value→ [1, 3, 4, 6, 8]s = [1, 3, 4, 6, 8];4    let double→ [12, 16]d: Vec<i32> = values.iter().copied().filter(|value| *value >= min).map(|value| value * 2).collect();5    println!("{:?}", doubled);6}
    output[12, 16]
filter `filter` keeps only values that satisfy the predicate.
map `map` transforms each surviving value into a new value.
collect `collect` materializes the lazy iterator pipeline into a `Vec<i32>`.