Added p_iter and q_iter

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.2 (unreleased)
+
+- Added `p_iter` and `q_iter`
+
 ## 0.2.1 (2021-11-15)
 
 - Added `Error` trait to errors

README.md

@@ -40,8 +40,8 @@ model.predict(row_index, column_index);
 Get the latent factors (these approximate the training matrix)
 
 ```rust
-model.p_factors();
-model.q_factors();
+model.p_iter().collect::<Vec<&[f32]>>();
+model.q_iter().collect::<Vec<&[f32]>>();
 ```
 
 Get the bias (average of all elements in the training matrix)

src/model.rs

@@ -2,6 +2,7 @@ use crate::bindings::*;
 use crate::{Error, Matrix, Params};
 use std::ffi::CString;
 use std::path::Path;
+use std::slice::Chunks;
 
 #[derive(Debug)]
 pub struct Model {
@@ -53,6 +54,14 @@ impl Model {
         unsafe { (*self.model).b }
     }
 
+    pub fn p_iter(&self) -> Chunks<'_, f32> {
+        self.p_factors().chunks(self.factors() as usize)
+    }
+
+    pub fn q_iter(&self) -> Chunks<'_, f32> {
+        self.q_factors().chunks(self.factors() as usize)
+    }
+
     pub fn p_factors(&self) -> &[f32] {
         unsafe { std::slice::from_raw_parts((*self.model).p, (self.rows() * self.factors()) as usize) }
     }
@@ -123,9 +132,31 @@ mod tests {
         let model = Model::params().quiet(true).fit(&data).unwrap();
         model.predict(0, 1);
 
-        model.p_factors();
-        model.q_factors();
-        model.bias();
+        // TODO assert in delta
+        assert_eq!(4.0 / 3.0, model.bias());
+
+        let p_factors = model.p_factors();
+        let q_factors = model.q_factors();
+
+        assert_eq!(model.p_iter().len(), 2);
+        assert_eq!(model.q_iter().len(), 2);
+
+        let p_vec = model.p_iter().collect::<Vec<&[f32]>>();
+        let q_vec = model.q_iter().collect::<Vec<&[f32]>>();
+
+        assert_eq!(p_vec[0], &p_factors[0..8]);
+        assert_eq!(p_vec[1], &p_factors[8..]);
+
+        assert_eq!(q_vec[0], &q_factors[0..8]);
+        assert_eq!(q_vec[1], &q_factors[8..]);
+
+        for (i, factors) in model.p_iter().enumerate() {
+            assert_eq!(factors, p_vec[i]);
+        }
+
+        for (i, factors) in model.q_iter().enumerate() {
+            assert_eq!(factors, q_vec[i]);
+        }
     }
 
     #[test]