From fcdc8b366adfe108bd901dae12a5276be3e8f0a4 Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Sun, 5 Oct 2025 20:11:38 +0200
Subject: [PATCH] feat: add RandomDistributionPerturbation

For vectors of reals, perturb by a random distribution with
expectation in 0.
---
 env/Cargo.lock              | 18 ++++++++++++++++++
 env/Cargo.toml              |  1 +
 env/src/perturbation/mod.rs | 26 +++++++++++++++++++++++++-
 3 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/env/Cargo.lock b/env/Cargo.lock
index d3a0305ee88a5b66174126493a548d3a1ceddf5a..124fe99fc62cfc5d1c3e0ad6514de6917d1a22d7 100644
--- a/env/Cargo.lock
+++ b/env/Cargo.lock
@@ -35,6 +35,7 @@ version = "0.1.0"
 dependencies = [
  "nalgebra",
  "rand",
+ "rand_distr",
 ]
 
 [[package]]
@@ -55,6 +56,12 @@ version = "0.2.176"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "58f929b4d672ea937a23a1ab494143d968337a5f47e56d0815df1e0890ddf174"
 
+[[package]]
+name = "libm"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
+
 [[package]]
 name = "matrixmultiply"
 version = "0.3.10"
@@ -138,6 +145,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -208,6 +216,16 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rand_distr"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a8615d50dcf34fa31f7ab52692afec947c4dd0ab803cc87cb3b0b4570ff7463"
+dependencies = [
+ "num-traits",
+ "rand",
+]
+
 [[package]]
 name = "rawpointer"
 version = "0.2.1"
diff --git a/env/Cargo.toml b/env/Cargo.toml
index 5bcb1a8e759d622a83fe024cd3e970f45c403cbf..18c352cdb80e8e50d69de3ca91252c6f3c2e0d7e 100644
--- a/env/Cargo.toml
+++ b/env/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2024"
 [dependencies]
 nalgebra = "0.33.2"
 rand = "0.9.2"
+rand_distr = "0.5.1"
diff --git a/env/src/perturbation/mod.rs b/env/src/perturbation/mod.rs
index d42907b872230b4cd55921b5163bf21d864bd02a..25e202cda3db32995312908f2638289ca49bf54a 100644
--- a/env/src/perturbation/mod.rs
+++ b/env/src/perturbation/mod.rs
@@ -1,4 +1,6 @@
-use rand::Rng;
+use nalgebra::SVector;
+use rand::{distr::Distribution, Rng};
+use rand_distr::{Normal, NormalError};
 
 use crate::binary_string::BinaryString;
 
@@ -30,6 +32,28 @@ impl<TRng: Rng> PerturbationOperator for BinaryStringBitPerturbation<TRng> {
     }
 }
 
+pub struct RandomDistributionPerturbation<const LEN: usize, TRng: Rng, TDistribution: Distribution<f64>> {
+    distribution: TDistribution,
+    rng: TRng
+}
+
+impl<const LEN: usize> RandomDistributionPerturbation<LEN, rand::rngs::ThreadRng, Normal<f64>> {
+    pub fn normal(variance: f64) -> Result<Self, NormalError> {
+        Ok(Self {
+            distribution: Normal::new(0.0, variance)?,
+            rng: rand::rng()
+        })
+    }
+}
+
+impl<TRng: Rng, TDistribution: Distribution<f64>, const LEN: usize> PerturbationOperator for RandomDistributionPerturbation<LEN, TRng, TDistribution> {
+    type Chromosome = SVector<f64, LEN>;
+
+    fn perturb(self: &mut Self, chromosome: &Self::Chromosome) -> Self::Chromosome {
+        chromosome + Self::Chromosome::zeros().map(|_| self.distribution.sample(&mut self.rng))
+    }
+}
+
 #[cfg(test)]
 pub mod tests {
     use crate::binary_string::BinaryString;