feat: Make SerDe optional

src/math/distance/euclidian.rs

@@ -18,14 +18,15 @@
 //!
 //! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
 //! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
-use serde::{Deserialize, Serialize};
+#[cfg(feature = "serde")] use serde::{Deserialize, Serialize};
 
 use crate::math::num::RealNumber;
 
 use super::Distance;
 
 /// Euclidean distance is a measure of the true straight line distance between two points in Euclidean n-space.
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone)]
 pub struct Euclidian {}
 
 impl Euclidian {

src/math/distance/hamming.rs

@@ -19,14 +19,15 @@
 //! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
 //! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
 
-use serde::{Deserialize, Serialize};
+#[cfg(feature = "serde")] use serde::{Deserialize, Serialize};
 
 use crate::math::num::RealNumber;
 
 use super::Distance;
 
 /// While comparing two integer-valued vectors of equal length, Hamming distance is the number of bit positions in which the two bits are different
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone)]
 pub struct Hamming {}
 
 impl<T: PartialEq, F: RealNumber> Distance<Vec<T>, F> for Hamming {

src/math/distance/mahalanobis.rs

@@ -44,7 +44,7 @@
 
 use std::marker::PhantomData;
 
-use serde::{Deserialize, Serialize};
+#[cfg(feature = "serde")] use serde::{Deserialize, Serialize};
 
 use crate::math::num::RealNumber;
 
@@ -52,7 +52,8 @@ use super::Distance;
 use crate::linalg::Matrix;
 
 /// Mahalanobis distance.
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone)]
 pub struct Mahalanobis<T: RealNumber, M: Matrix<T>> {
     /// covariance matrix of the dataset
     pub sigma: M,

src/math/distance/manhattan.rs

@@ -17,14 +17,15 @@
 //! ```
 //! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
 //! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
-use serde::{Deserialize, Serialize};
+#[cfg(feature = "serde")] use serde::{Deserialize, Serialize};
 
 use crate::math::num::RealNumber;
 
 use super::Distance;
 
 /// Manhattan distance
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone)]
 pub struct Manhattan {}
 
 impl<T: RealNumber> Distance<Vec<T>, T> for Manhattan {

src/math/distance/minkowski.rs

@@ -21,14 +21,15 @@
 //! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
 //! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
 
-use serde::{Deserialize, Serialize};
+#[cfg(feature = "serde")] use serde::{Deserialize, Serialize};
 
 use crate::math::num::RealNumber;
 
 use super::Distance;
 
 /// Defines the Minkowski distance of order `p`
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone)]
 pub struct Minkowski {
     /// order, integer
     pub p: u16,