--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/merging.rs Fri Nov 28 12:48:17 2025 -0500
@@ -0,0 +1,316 @@
+/*!
+Spike merging heuristics for [`DiscreteMeasure`]s.
+
+This module primarily provides the [`SpikeMerging`] trait, and within it,
+the [`SpikeMerging::merge_spikes`] method. The trait is implemented on
+[`DiscreteMeasure<Loc<N, F>, F>`]s in dimensions `N=1` and `N=2`.
+*/
+
+use numeric_literals::replace_float_literals;
+use serde::{Deserialize, Serialize};
+use std::cmp::Ordering;
+//use clap::builder::{PossibleValuesParser, PossibleValue};
+use alg_tools::nanleast::NaNLeast;
+
+use super::delta::*;
+use super::discrete::*;
+use alg_tools::loc::Loc;
+use alg_tools::types::*;
+
+/// Spike merging heuristic selection
+#[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize, Debug)]
+#[allow(dead_code)]
+pub struct SpikeMergingMethod<F> {
+ // Merging radius
+ pub radius: F,
+ // Enabled
+ pub enabled: bool,
+ // Interpolate merged points
+ pub interp: bool,
+}
+
+#[replace_float_literals(F::cast_from(literal))]
+impl<F: Float> Default for SpikeMergingMethod<F> {
+ fn default() -> Self {
+ SpikeMergingMethod { radius: 0.01, enabled: false, interp: true }
+ }
+}
+
+/// Trait for dimension-dependent implementation of heuristic peak merging strategies.
+pub trait SpikeMerging<F> {
+ /// Attempt spike merging according to [`SpikeMerging`] method.
+ ///
+ /// Returns the last [`Some`] returned by the merging candidate acceptance decision closure
+ /// `accept` if any merging is performed. The closure should accept as its only parameter a
+ /// new candidate measure (it will generally be internally mutated `self`, although this is
+ /// not guaranteed), and return [`None`] if the merge is accepted, and otherwise a [`Some`] of
+ /// an arbitrary value. This method will return that value for the *last* accepted merge, or
+ /// [`None`] if no merge was accepted.
+ ///
+ /// This method is stable with respect to spike locations: on merge, the weights of existing
+ /// removed spikes is set to zero, new ones inserted at the end of the spike vector.
+ /// They merge may also be performed by increasing the weights of the existing spikes,
+ /// without inserting new spikes.
+ fn merge_spikes<G>(&mut self, method: SpikeMergingMethod<F>, accept: G) -> usize
+ where
+ G: FnMut(&'_ Self) -> bool,
+ {
+ if method.enabled {
+ self.do_merge_spikes_radius(method.radius, method.interp, accept)
+ } else {
+ 0
+ }
+ }
+
+ /// Attempt to merge spikes based on a value and a fitness function.
+ ///
+ /// Calls [`SpikeMerging::merge_spikes`] with `accept` constructed from the composition of
+ /// `value` and `fitness`, compared to initial fitness. Returns the last return value of `value`
+ // for a merge accepted by `fitness`. If no merge was accepted, `value` applied to the initial
+ /// `self` is returned. also the number of merges is returned;
+ fn merge_spikes_fitness<G, H, V, O>(
+ &mut self,
+ method: SpikeMergingMethod<F>,
+ value: G,
+ fitness: H,
+ ) -> (V, usize)
+ where
+ G: Fn(&'_ Self) -> V,
+ H: Fn(&'_ V) -> O,
+ O: PartialOrd,
+ {
+ let mut res = value(self);
+ let initial_fitness = fitness(&res);
+ let count = self.merge_spikes(method, |μ| {
+ res = value(μ);
+ fitness(&res) <= initial_fitness
+ });
+ (res, count)
+ }
+
+ /// Attempt to merge spikes that are within radius $ρ$ of each other (unspecified norm).
+ ///
+ /// This method implements [`SpikeMerging::merge_spikes`].
+ fn do_merge_spikes_radius<G>(&mut self, ρ: F, interp: bool, accept: G) -> usize
+ where
+ G: FnMut(&'_ Self) -> bool;
+}
+
+#[replace_float_literals(F::cast_from(literal))]
+impl<F: Float, const N: usize> DiscreteMeasure<Loc<N, F>, F> {
+ /// Attempts to merge spikes with indices `i` and `j`.
+ ///
+ /// This assumes that the weights of the two spikes have already been checked not to be zero.
+ ///
+ /// The parameter `res` points to the current “result” for [`SpikeMerging::merge_spikes`].
+ /// If the merge is accepted by `accept` returning a [`Some`], `res` will be replaced by its
+ /// return value.
+ ///
+ /// Returns the index of `self.spikes` storing the new spike.
+ fn attempt_merge<G>(
+ &mut self,
+ i: usize,
+ j: usize,
+ interp: bool,
+ accept: &mut G,
+ ) -> Option<usize>
+ where
+ G: FnMut(&'_ Self) -> bool,
+ {
+ let &DeltaMeasure { x: xi, α: αi } = &self.spikes[i];
+ let &DeltaMeasure { x: xj, α: αj } = &self.spikes[j];
+
+ if interp {
+ // Merge inplace
+ self.spikes[i].α = 0.0;
+ self.spikes[j].α = 0.0;
+ let αia = αi.abs();
+ let αja = αj.abs();
+ self.spikes
+ .push(DeltaMeasure { α: αi + αj, x: (xi * αia + xj * αja) / (αia + αja) });
+ if accept(self) {
+ Some(self.spikes.len() - 1)
+ } else {
+ // Merge not accepted, restore modification
+ self.spikes[i].α = αi;
+ self.spikes[j].α = αj;
+ self.spikes.pop();
+ None
+ }
+ } else {
+ // Attempt merge inplace, first combination
+ self.spikes[i].α = αi + αj;
+ self.spikes[j].α = 0.0;
+ if accept(self) {
+ // Merge accepted
+ Some(i)
+ } else {
+ // Attempt merge inplace, second combination
+ self.spikes[i].α = 0.0;
+ self.spikes[j].α = αi + αj;
+ if accept(self) {
+ // Merge accepted
+ Some(j)
+ } else {
+ // Merge not accepted, restore modification
+ self.spikes[i].α = αi;
+ self.spikes[j].α = αj;
+ None
+ }
+ }
+ }
+ }
+}
+
+/// Sorts a vector of indices into `slice` by `compare`.
+///
+/// The closure `compare` operators on references to elements of `slice`.
+/// Returns the sorted vector of indices into `slice`.
+pub fn sort_indices_by<V, F>(slice: &[V], mut compare: F) -> Vec<usize>
+where
+ F: FnMut(&V, &V) -> Ordering,
+{
+ let mut indices = Vec::from_iter(0..slice.len());
+ indices.sort_by(|&i, &j| compare(&slice[i], &slice[j]));
+ indices
+}
+
+#[replace_float_literals(F::cast_from(literal))]
+impl<F: Float> SpikeMerging<F> for DiscreteMeasure<Loc<1, F>, F> {
+ fn do_merge_spikes_radius<G>(&mut self, ρ: F, interp: bool, mut accept: G) -> usize
+ where
+ G: FnMut(&'_ Self) -> bool,
+ {
+ // Sort by coordinate into an indexing array.
+ let mut indices = sort_indices_by(&self.spikes, |&δ1, &δ2| {
+ let &Loc([x1]) = &δ1.x;
+ let &Loc([x2]) = &δ2.x;
+ // nan-ignoring ordering of floats
+ NaNLeast(x1).cmp(&NaNLeast(x2))
+ });
+
+ // Initialise result
+ let mut count = 0;
+
+ // Scan consecutive pairs and merge if close enough and accepted by `accept`.
+ if indices.len() == 0 {
+ return count;
+ }
+ for k in 0..(indices.len() - 1) {
+ let i = indices[k];
+ let j = indices[k + 1];
+ let &DeltaMeasure { x: Loc([xi]), α: αi } = &self.spikes[i];
+ let &DeltaMeasure { x: Loc([xj]), α: αj } = &self.spikes[j];
+ debug_assert!(xi <= xj);
+ // If close enough, attempt merging
+ if αi != 0.0 && αj != 0.0 && xj <= xi + ρ {
+ if let Some(l) = self.attempt_merge(i, j, interp, &mut accept) {
+ // For this to work (the debug_assert! to not trigger above), the new
+ // coordinate produced by attempt_merge has to be at most xj.
+ indices[k + 1] = l;
+ count += 1
+ }
+ }
+ }
+
+ count
+ }
+}
+
+/// Orders `δ1` and `δ1` according to the first coordinate.
+fn compare_first_coordinate<F: Float>(
+ δ1: &DeltaMeasure<Loc<2, F>, F>,
+ δ2: &DeltaMeasure<Loc<2, F>, F>,
+) -> Ordering {
+ let &Loc([x11, ..]) = &δ1.x;
+ let &Loc([x21, ..]) = &δ2.x;
+ // nan-ignoring ordering of floats
+ NaNLeast(x11).cmp(&NaNLeast(x21))
+}
+
+#[replace_float_literals(F::cast_from(literal))]
+impl<F: Float> SpikeMerging<F> for DiscreteMeasure<Loc<2, F>, F> {
+ fn do_merge_spikes_radius<G>(&mut self, ρ: F, interp: bool, mut accept: G) -> usize
+ where
+ G: FnMut(&'_ Self) -> bool,
+ {
+ // Sort by first coordinate into an indexing array.
+ let mut indices = sort_indices_by(&self.spikes, compare_first_coordinate);
+
+ // Initialise result
+ let mut count = 0;
+ let mut start_scan_2nd = 0;
+
+ // Scan in order
+ if indices.len() == 0 {
+ return count;
+ }
+ for k in 0..indices.len() - 1 {
+ let i = indices[k];
+ let &DeltaMeasure { x: Loc([xi1, xi2]), α: αi } = &self[i];
+
+ if αi == 0.0 {
+ // Nothin to be done if the weight is already zero
+ continue;
+ }
+
+ let mut closest = None;
+
+ // Scan for second spike. We start from `start_scan_2nd + 1` with `start_scan_2nd`
+ // the smallest invalid merging index on the previous loop iteration, because a
+ // the _closest_ mergeable spike might have index less than `k` in `indices`, and a
+ // merge with it might have not been attempted with this spike if a different closer
+ // spike was discovered based on the second coordinate.
+ 'scan_2nd: for l in (start_scan_2nd + 1)..indices.len() {
+ if l == k {
+ // Do not attempt to merge a spike with itself
+ continue;
+ }
+ let j = indices[l];
+ let &DeltaMeasure { x: Loc([xj1, xj2]), α: αj } = &self[j];
+
+ if xj1 < xi1 - ρ {
+ // Spike `j = indices[l]` has too low first coordinate. Update starting index
+ // for next iteration, and continue scanning.
+ start_scan_2nd = l;
+ continue 'scan_2nd;
+ } else if xj1 > xi1 + ρ {
+ // Break out: spike `j = indices[l]` has already too high first coordinate, no
+ // more close enough spikes can be found due to the sorting of `indices`.
+ break 'scan_2nd;
+ }
+
+ // If also second coordinate is close enough, attempt merging if closer than
+ // previously discovered mergeable spikes.
+ let d2 = (xi2 - xj2).abs();
+ if αj != 0.0 && d2 <= ρ {
+ let r1 = xi1 - xj1;
+ let d = (d2 * d2 + r1 * r1).sqrt();
+ match closest {
+ None => closest = Some((l, j, d)),
+ Some((_, _, r)) if r > d => closest = Some((l, j, d)),
+ _ => {}
+ }
+ }
+ }
+
+ // Attempt merging closest close-enough spike
+ if let Some((l, j, _)) = closest {
+ if let Some(n) = self.attempt_merge(i, j, interp, &mut accept) {
+ // If merge was succesfull, make new spike candidate for merging.
+ indices[l] = n;
+ count += 1;
+ let compare = |i, j| compare_first_coordinate(&self.spikes[i], &self.spikes[j]);
+ // Re-sort relevant range of indices
+ if l < k {
+ indices[l..k].sort_by(|&i, &j| compare(i, j));
+ } else {
+ indices[k + 1..=l].sort_by(|&i, &j| compare(i, j));
+ }
+ }
+ }
+ }
+
+ count
+ }
+}