Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
335: Powerset iterator adaptor r=jswrenn a=willcrozi Implements a [powerset](https://en.wikipedia.org/wiki/Power_set) iterator adaptor that iterates over all subsets of the input iterator's elements. Returns vectors representing these subsets. Internally uses `Combinations` of increasing length. I've taken the strategy of using a 'position' field that acts both as a means to to detect the special case of the first element and also allows optimal `size_hint()` implementation. Additionally there is a commit to improve performance that alters `Combinations` implementation slightly. I've added Combinations benchmark as a stand-alone commit to allow checking for performance regressions. `Powerset` performance after this commit improves some cases (with small sizes of `n`) by 10-30% This is my first attempt at a Rust contribution, happy to put in whatever discussion/work to get this merged. Cheers! Co-authored-by: Will Crozier <willcrozi@gmail.com>
- Loading branch information
Showing
11 changed files
with
416 additions
and
36 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,125 @@ | ||
use criterion::{black_box, criterion_group, criterion_main, Criterion}; | ||
use itertools::Itertools; | ||
|
||
// approximate 100_000 iterations for each combination | ||
const N1: usize = 100_000; | ||
const N2: usize = 448; | ||
const N3: usize = 86; | ||
const N4: usize = 41; | ||
const N14: usize = 21; | ||
|
||
fn comb_for1(c: &mut Criterion) { | ||
c.bench_function("comb for1", move |b| { | ||
b.iter(|| { | ||
for i in 0..N1 { | ||
black_box(vec![i]); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_for2(c: &mut Criterion) { | ||
c.bench_function("comb for2", move |b| { | ||
b.iter(|| { | ||
for i in 0..N2 { | ||
for j in (i + 1)..N2 { | ||
black_box(vec![i, j]); | ||
} | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_for3(c: &mut Criterion) { | ||
c.bench_function("comb for3", move |b| { | ||
b.iter(|| { | ||
for i in 0..N3 { | ||
for j in (i + 1)..N3 { | ||
for k in (j + 1)..N3 { | ||
black_box(vec![i, j, k]); | ||
} | ||
} | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_for4(c: &mut Criterion) { | ||
c.bench_function("comb for4", move |b| { | ||
b.iter(|| { | ||
for i in 0..N4 { | ||
for j in (i + 1)..N4 { | ||
for k in (j + 1)..N4 { | ||
for l in (k + 1)..N4 { | ||
black_box(vec![i, j, k, l]); | ||
} | ||
} | ||
} | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_c1(c: &mut Criterion) { | ||
c.bench_function("comb c1", move |b| { | ||
b.iter(|| { | ||
for combo in (0..N1).combinations(1) { | ||
black_box(combo); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_c2(c: &mut Criterion) { | ||
c.bench_function("comb c2", move |b| { | ||
b.iter(|| { | ||
for combo in (0..N2).combinations(2) { | ||
black_box(combo); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_c3(c: &mut Criterion) { | ||
c.bench_function("comb c3", move |b| { | ||
b.iter(|| { | ||
for combo in (0..N3).combinations(3) { | ||
black_box(combo); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_c4(c: &mut Criterion) { | ||
c.bench_function("comb c4", move |b| { | ||
b.iter(|| { | ||
for combo in (0..N4).combinations(4) { | ||
black_box(combo); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn comb_c14(c: &mut Criterion) { | ||
c.bench_function("comb c14", move |b| { | ||
b.iter(|| { | ||
for combo in (0..N14).combinations(14) { | ||
black_box(combo); | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
criterion_group!( | ||
benches, | ||
comb_for1, | ||
comb_for2, | ||
comb_for3, | ||
comb_for4, | ||
comb_c1, | ||
comb_c2, | ||
comb_c3, | ||
comb_c4, | ||
comb_c14, | ||
); | ||
criterion_main!(benches); |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,44 @@ | ||
use criterion::{black_box, criterion_group, criterion_main, Criterion}; | ||
use itertools::Itertools; | ||
|
||
// Keep aggregate generated elements the same, regardless of powerset length. | ||
const TOTAL_ELEMENTS: usize = 1 << 12; | ||
const fn calc_iters(n: usize) -> usize { | ||
TOTAL_ELEMENTS / (1 << n) | ||
} | ||
|
||
fn powerset_n(c: &mut Criterion, n: usize) { | ||
let id = format!("powerset {}", n); | ||
c.bench_function(id.as_str(), move |b| { | ||
b.iter(|| { | ||
for _ in 0..calc_iters(n) { | ||
for elt in (0..n).powerset() { | ||
black_box(elt); | ||
} | ||
} | ||
}) | ||
}); | ||
} | ||
|
||
fn powerset_0(c: &mut Criterion) { powerset_n(c, 0); } | ||
|
||
fn powerset_1(c: &mut Criterion) { powerset_n(c, 1); } | ||
|
||
fn powerset_2(c: &mut Criterion) { powerset_n(c, 2); } | ||
|
||
fn powerset_4(c: &mut Criterion) { powerset_n(c, 4); } | ||
|
||
fn powerset_8(c: &mut Criterion) { powerset_n(c, 8); } | ||
|
||
fn powerset_12(c: &mut Criterion) { powerset_n(c, 12); } | ||
|
||
criterion_group!( | ||
benches, | ||
powerset_0, | ||
powerset_1, | ||
powerset_2, | ||
powerset_4, | ||
powerset_8, | ||
powerset_12, | ||
); | ||
criterion_main!(benches); |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.