84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
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//! Test functionality for generating random Monge matrices.
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// The code is put here so we can reuse it in different integration
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// tests, without Cargo finding it when `cargo test` is run. See the
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// section on "Submodules in Integration Tests" in
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// https://doc.rust-lang.org/book/ch11-03-test-organization.html
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use ndarray::{s, Array2};
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use num_traits::PrimInt;
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use rand::distributions::{Distribution, Standard};
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use rand::Rng;
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/// A Monge matrix can be decomposed into one of these primitive
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/// building blocks.
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#[derive(Copy, Clone)]
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pub enum MongePrim {
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ConstantRows,
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ConstantCols,
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UpperRightOnes,
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LowerLeftOnes,
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}
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impl MongePrim {
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/// Generate a Monge matrix from a primitive.
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pub fn to_matrix<T: PrimInt, R: Rng>(&self, m: usize, n: usize, rng: &mut R) -> Array2<T>
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where
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Standard: Distribution<T>,
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{
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let mut matrix = Array2::from_elem((m, n), T::zero());
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// Avoid panic in UpperRightOnes and LowerLeftOnes below.
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if m == 0 || n == 0 {
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return matrix;
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}
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match *self {
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MongePrim::ConstantRows => {
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for mut row in matrix.rows_mut() {
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if rng.gen::<bool>() {
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row.fill(T::one())
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}
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}
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}
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MongePrim::ConstantCols => {
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for mut col in matrix.columns_mut() {
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if rng.gen::<bool>() {
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col.fill(T::one())
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}
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}
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}
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MongePrim::UpperRightOnes => {
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let i = rng.gen_range(0..(m + 1) as isize);
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let j = rng.gen_range(0..(n + 1) as isize);
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matrix.slice_mut(s![..i, -j..]).fill(T::one());
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}
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MongePrim::LowerLeftOnes => {
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let i = rng.gen_range(0..(m + 1) as isize);
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let j = rng.gen_range(0..(n + 1) as isize);
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matrix.slice_mut(s![-i.., ..j]).fill(T::one());
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}
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}
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matrix
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}
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}
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/// Generate a random Monge matrix.
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pub fn random_monge_matrix<R: Rng, T: PrimInt>(m: usize, n: usize, rng: &mut R) -> Array2<T>
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where
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Standard: Distribution<T>,
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{
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let monge_primitives = [
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MongePrim::ConstantRows,
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MongePrim::ConstantCols,
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MongePrim::LowerLeftOnes,
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MongePrim::UpperRightOnes,
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];
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let mut matrix = Array2::from_elem((m, n), T::zero());
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for _ in 0..(m + n) {
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let monge = monge_primitives[rng.gen_range(0..monge_primitives.len())];
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matrix = matrix + monge.to_matrix(m, n, rng);
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}
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matrix
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}
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