Handle kernel serialization (#232)

* Handle kernel serialization
* Do not use typetag in WASM
* enable tests for serialization
* Update serde feature deps

Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>
Co-authored-by: Lorenzo <tunedconsulting@gmail.com>

Author: morenol

Cargo.toml

@@ -29,9 +29,12 @@ rand = { version = "0.8.5", default-features = false, features = ["small_rng"] }
 rand_distr = { version = "0.4", optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+typetag = { version = "0.2", optional = true }
+
 [features]
 default = []
-serde = ["dep:serde"]
+serde = ["dep:serde", "dep:typetag"]
 ndarray-bindings = ["dep:ndarray"]
 datasets = ["dep:rand_distr", "std_rand", "serde"]
 std_rand = ["rand/std_rng", "rand/std"]

src/svm/mod.rs

@@ -30,8 +30,6 @@ pub mod svr;
 
 use core::fmt::Debug;
 
-#[cfg(feature = "serde")]
-use serde::ser::{SerializeStruct, Serializer};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
@@ -40,36 +38,20 @@ use crate::linalg::basic::arrays::{Array1, ArrayView1};
 
 /// Defines a kernel function.
 /// This is a object-safe trait.
-pub trait Kernel {
+#[cfg_attr(
+    all(feature = "serde", not(target_arch = "wasm32")),
+    typetag::serde(tag = "type")
+)]
+pub trait Kernel: Debug {
     #[allow(clippy::ptr_arg)]
     /// Apply kernel function to x_i and x_j
     fn apply(&self, x_i: &Vec<f64>, x_j: &Vec<f64>) -> Result<f64, Failed>;
-    /// Return a serializable name
-    fn name(&self) -> &'static str;
-}
-
-impl Debug for dyn Kernel {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        write!(f, "Kernel<f64>")
-    }
-}
-
-#[cfg(feature = "serde")]
-impl Serialize for dyn Kernel {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        let mut s = serializer.serialize_struct("Kernel", 1)?;
-        s.serialize_field("type", &self.name())?;
-        s.end()
-    }
 }
 
 /// Pre-defined kernel functions
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[derive(Debug, Clone)]
-pub struct Kernels {}
+pub struct Kernels;
 
 impl Kernels {
     /// Return a default linear
@@ -211,15 +193,14 @@ impl SigmoidKernel {
     }
 }
 
+#[cfg_attr(all(feature = "serde", not(target_arch = "wasm32")), typetag::serde)]
 impl Kernel for LinearKernel {
     fn apply(&self, x_i: &Vec<f64>, x_j: &Vec<f64>) -> Result<f64, Failed> {
         Ok(x_i.dot(x_j))
     }
-    fn name(&self) -> &'static str {
-        "Linear"
-    }
 }
 
+#[cfg_attr(all(feature = "serde", not(target_arch = "wasm32")), typetag::serde)]
 impl Kernel for RBFKernel {
     fn apply(&self, x_i: &Vec<f64>, x_j: &Vec<f64>) -> Result<f64, Failed> {
         if self.gamma.is_none() {
@@ -231,11 +212,9 @@ impl Kernel for RBFKernel {
         let v_diff = x_i.sub(x_j);
         Ok((-self.gamma.unwrap() * v_diff.mul(&v_diff).sum()).exp())
     }
-    fn name(&self) -> &'static str {
-        "RBF"
-    }
 }
 
+#[cfg_attr(all(feature = "serde", not(target_arch = "wasm32")), typetag::serde)]
 impl Kernel for PolynomialKernel {
     fn apply(&self, x_i: &Vec<f64>, x_j: &Vec<f64>) -> Result<f64, Failed> {
         if self.gamma.is_none() || self.coef0.is_none() || self.degree.is_none() {
@@ -247,11 +226,9 @@ impl Kernel for PolynomialKernel {
         let dot = x_i.dot(x_j);
         Ok((self.gamma.unwrap() * dot + self.coef0.unwrap()).powf(self.degree.unwrap()))
     }
-    fn name(&self) -> &'static str {
-        "Polynomial"
-    }
 }
 
+#[cfg_attr(all(feature = "serde", not(target_arch = "wasm32")), typetag::serde)]
 impl Kernel for SigmoidKernel {
     fn apply(&self, x_i: &Vec<f64>, x_j: &Vec<f64>) -> Result<f64, Failed> {
         if self.gamma.is_none() || self.coef0.is_none() {
@@ -263,9 +240,6 @@ impl Kernel for SigmoidKernel {
         let dot = x_i.dot(x_j);
         Ok(self.gamma.unwrap() * dot + self.coef0.unwrap().tanh())
     }
-    fn name(&self) -> &'static str {
-        "Sigmoid"
-    }
 }
 
 #[cfg(test)]

src/svm/svc.rs

@@ -100,8 +100,11 @@ pub struct SVCParameters<TX: Number + RealNumber, TY: Number + Ord, X: Array2<TX
     pub c: TX,
     /// Tolerance for stopping criterion.
     pub tol: TX,
-    #[cfg_attr(feature = "serde", serde(skip_deserializing))]
     /// The kernel function.
+    #[cfg_attr(
+        all(feature = "serde", target_arch = "wasm32"),
+        serde(skip_serializing, skip_deserializing)
+    )]
     pub kernel: Option<Box<dyn Kernel>>,
     /// Unused parameter.
     m: PhantomData<(X, Y, TY)>,
@@ -1085,7 +1088,7 @@ mod tests {
         wasm_bindgen_test::wasm_bindgen_test
     )]
     #[test]
-    #[cfg(feature = "serde")]
+    #[cfg(all(feature = "serde", not(target_arch = "wasm32")))]
     fn svc_serde() {
         let x = DenseMatrix::from_2d_array(&[
             &[5.1, 3.5, 1.4, 0.2],
@@ -1119,8 +1122,9 @@ mod tests {
         let svc = SVC::fit(&x, &y, &params).unwrap();
 
         // serialization
-        let serialized_svc = &serde_json::to_string(&svc).unwrap();
+        let deserialized_svc: SVC<f64, i32, _, _> =
+            serde_json::from_str(&serde_json::to_string(&svc).unwrap()).unwrap();
 
-        println!("{:?}", serialized_svc);
+        assert_eq!(svc, deserialized_svc);
     }
 }

src/svm/svr.rs

@@ -92,8 +92,11 @@ pub struct SVRParameters<T: Number + FloatNumber + PartialOrd> {
     pub c: T,
     /// Tolerance for stopping criterion.
     pub tol: T,
-    #[cfg_attr(feature = "serde", serde(skip_deserializing))]
     /// The kernel function.
+    #[cfg_attr(
+        all(feature = "serde", target_arch = "wasm32"),
+        serde(skip_serializing, skip_deserializing)
+    )]
     pub kernel: Option<Box<dyn Kernel>>,
 }
 
@@ -668,7 +671,7 @@ mod tests {
         wasm_bindgen_test::wasm_bindgen_test
     )]
     #[test]
-    #[cfg(feature = "serde")]
+    #[cfg(all(feature = "serde", not(target_arch = "wasm32")))]
     fn svr_serde() {
         let x = DenseMatrix::from_2d_array(&[
             &[234.289, 235.6, 159.0, 107.608, 1947., 60.323],
@@ -699,13 +702,9 @@ mod tests {
 
         let svr = SVR::fit(&x, &y, &params).unwrap();
 
-        let serialized = &serde_json::to_string(&svr).unwrap();
-
-        println!("{}", &serialized);
-
-        // let deserialized_svr: SVR<f64, DenseMatrix<f64>, LinearKernel> =
-        //     serde_json::from_str(&serde_json::to_string(&svr).unwrap()).unwrap();
+        let deserialized_svr: SVR<f64, DenseMatrix<f64>, _> =
+            serde_json::from_str(&serde_json::to_string(&svr).unwrap()).unwrap();
 
-        // assert_eq!(svr, deserialized_svr);
+        assert_eq!(svr, deserialized_svr);
     }
 }