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use crate::arrayadapter::ArrayAdapter;
use crate::fastermsc::{initial_assignment,update_removal_loss,find_best_swap,do_swap};
use crate::fastermsc::{initial_assignment_k2,find_best_swap_k2,do_swap_k2};
use crate::util::*;
use core::ops::AddAssign;
use num_traits::{Signed, Zero, Float};
use std::convert::From;
pub fn fastmsc<M, N, L>(
mat: &M,
med: &mut Vec<usize>,
maxiter: usize,
) -> (L, Vec<usize>, usize, usize)
where
N: Zero + PartialOrd + Copy,
L: Float + Signed + AddAssign + From<N> + From<u32>,
M: ArrayAdapter<N>,
{
let (n, k) = (mat.len(), med.len());
if k == 1 {
let assi = vec![0; n];
let (swapped, loss) = choose_medoid_within_partition::<M, N, L>(mat, &assi, med, 0);
return (loss, assi, 1, if swapped { 1 } else { 0 });
}
if k == 2 {
return fastmsc_k2(mat, med, maxiter)
}
let (mut loss, mut data): (L,_) = initial_assignment(mat, med);
debug_assert_assignment_th(mat, med, &data);
let mut removal_loss = vec![L::zero(); k];
let (mut n_swaps, mut iter) = (0, 0);
while iter < maxiter {
iter += 1;
let mut best = (L::zero(), usize::MAX, usize::MAX);
update_removal_loss(&data, &mut removal_loss);
for j in 0..n {
if j == med[data[j].near.i as usize] {
continue; }
let (change, b) = find_best_swap(mat, &removal_loss, &data, j);
if change <= best.0 {
continue; }
best = (change, b, j);
}
if best.0 > L::zero() {
n_swaps += 1;
let newloss = do_swap(mat, med, &mut data, best.1, best.2);
if newloss >= loss {
break; }
loss = newloss;
} else {
break; }
}
let assi = data.iter().map(|x| x.near.i as usize).collect();
loss = L::one() - loss / <L as From<u32>>::from(n as u32);
(loss, assi, iter, n_swaps)
}
fn fastmsc_k2<M, N, L>(
mat: &M,
med: &mut Vec<usize>,
maxiter: usize,
) -> (L, Vec<usize>, usize, usize)
where
N: Zero + PartialOrd + Copy,
L: Float + Signed + AddAssign + From<N> + From<u32>,
M: ArrayAdapter<N>,
{
let (n, k) = (mat.len(), med.len());
assert!(k == 2, "Only valid for k=2");
let (mut loss, mut assi, mut data): (L,_,_) = initial_assignment_k2(mat, med);
let (mut n_swaps, mut iter) = (0, 0);
while iter < maxiter {
iter += 1;
let mut best = (L::zero(), k, usize::MAX);
for j in 0..n {
if j == med[assi[j] as usize] {
continue; }
let (newloss, b): (L, _) = find_best_swap_k2(mat, &data, j); if best.2 == usize::MAX || newloss < best.0 {
best = (newloss, b, j);
}
}
if !(best.0 < loss) {
break; }
n_swaps += 1;
let newloss = do_swap_k2(mat, med, &mut assi, &mut data, best.1, best.2);
if !(newloss < loss) {
break; }
loss = newloss;
}
loss = L::one() - loss / <L as From<u32>>::from(n as u32);
(loss, assi, iter, n_swaps)
}
#[cfg(test)]
mod tests {
use crate::{arrayadapter::LowerTriangle, fastmsc, silhouette, medoid_silhouette, util::assert_array};
#[test]
fn testfastpammedsil_simple() {
let data = LowerTriangle {
n: 5,
data: vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 1],
};
let mut meds = vec![0, 1, 2];
let (loss, assi, n_iter, n_swap): (f64, _, _, _) = fastmsc(&data, &mut meds, 10);
let (sil, _): (f64, _) = silhouette(&data, &assi, false);
let (msil, _): (f64, _) = medoid_silhouette(&data, &meds, false);
print!("FastMSC: {:?} {:?} {:?} {:?} {:?} {:?}", loss, n_iter, n_swap, sil, assi, meds);
assert_eq!(loss, 0.9047619047619048, "loss not as expected");
assert_eq!(msil, 0.9047619047619048, "Medoid Silhouette not as expected");
assert_eq!(n_swap, 1, "swaps not as expected");
assert_eq!(n_iter, 2, "iterations not as expected");
assert_array(assi, vec![0, 0, 2, 1, 1], "assignment not as expected");
assert_array(meds, vec![0, 3, 2], "medoids not as expected");
assert_eq!(sil, 0.8773115773115773, "Silhouette not as expected");
}
#[test]
fn testfastpammedsil_simple2() {
let data = LowerTriangle {
n: 5,
data: vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 1],
};
let mut meds = vec![0, 1];
let (loss, assi, n_iter, n_swap): (f64, _, _, _) = fastmsc(&data, &mut meds, 10);
let (sil, _): (f64, _) = silhouette(&data, &assi, false);
let (msil, _): (f64, _) = medoid_silhouette(&data, &meds, false);
print!("FastMSC: {:?} {:?} {:?} {:?} {:?} {:?}", loss, n_iter, n_swap, sil, assi, meds);
assert_eq!(loss, 0.8805555555555555, "loss not as expected");
assert_eq!(msil, 0.8805555555555555, "Medoid Silhouette not as expected");
assert_eq!(n_swap, 1, "swaps not as expected");
assert_eq!(n_iter, 2, "iterations not as expected");
assert_array(assi, vec![0, 0, 0, 1, 1], "assignment not as expected");
assert_array(meds, vec![0, 4], "medoids not as expected");
assert_eq!(sil, 0.7522494172494172, "Silhouette not as expected");
}
}