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#![cfg(feature = "ndarray")]
use ndarray::{s, Array2};
use rand::SeedableRng;
use rand_chacha::ChaCha20Rng;
use smawk::{brute_force, online_column_minima, recursive};
mod random_monge;
use random_monge::random_monge_matrix;
/// Check that the brute force, recursive, and SMAWK functions
/// give identical results on a large number of randomly generated
/// Monge matrices.
#[test]
fn column_minima_agree() {
let sizes = vec![1, 2, 3, 4, 5, 10, 15, 20, 30];
let mut rng = ChaCha20Rng::seed_from_u64(0);
for _ in 0..4 {
for m in sizes.clone().iter() {
for n in sizes.clone().iter() {
let matrix: Array2<i32> = random_monge_matrix(*m, *n, &mut rng);
// Compute and test row minima.
let brute_force = brute_force::row_minima(&matrix);
let recursive = recursive::row_minima(&matrix);
let smawk = smawk::row_minima(&matrix);
assert_eq!(
brute_force, recursive,
"recursive and brute force differs on:\n{:?}",
matrix
);
assert_eq!(
brute_force, smawk,
"SMAWK and brute force differs on:\n{:?}",
matrix
);
// Do the same for the column minima.
let brute_force = brute_force::column_minima(&matrix);
let recursive = recursive::column_minima(&matrix);
let smawk = smawk::column_minima(&matrix);
assert_eq!(
brute_force, recursive,
"recursive and brute force differs on:\n{:?}",
matrix
);
assert_eq!(
brute_force, smawk,
"SMAWK and brute force differs on:\n{:?}",
matrix
);
}
}
}
}
/// Check that the brute force and online SMAWK functions give
/// identical results on a large number of randomly generated
/// Monge matrices.
#[test]
fn online_agree() {
let sizes = vec![1, 2, 3, 4, 5, 10, 15, 20, 30, 50];
let mut rng = ChaCha20Rng::seed_from_u64(0);
for _ in 0..5 {
for &size in &sizes {
// Random totally monotone square matrix of the
// desired size.
let mut matrix: Array2<i32> = random_monge_matrix(size, size, &mut rng);
// Adjust matrix so the column minima are above the
// diagonal. The brute_force::column_minima will still
// work just fine on such a mangled Monge matrix.
let max = *matrix.iter().max().unwrap_or(&0);
for idx in 0..(size as isize) {
// Using the maximum value of the matrix instead
// of i32::max_value() makes for prettier matrices
// in case we want to print them.
matrix.slice_mut(s![idx..idx + 1, ..idx + 1]).fill(max);
}
// The online algorithm always returns the initial
// value for the left-most column -- without
// inspecting the column at all. So we fill the
// left-most column with this value to have the brute
// force algorithm do the same.
let initial = 42;
matrix.slice_mut(s![0.., ..1]).fill(initial);
// Brute-force computation of column minima, returned
// in the same form as online_column_minima.
let brute_force = brute_force::column_minima(&matrix)
.iter()
.enumerate()
.map(|(j, &i)| (i, matrix[[i, j]]))
.collect::<Vec<_>>();
let online = online_column_minima(initial, size, |_, i, j| matrix[[i, j]]);
assert_eq!(
brute_force, online,
"brute force and online differ on:\n{:3?}",
matrix
);
}
}
}
|
