No more SeriesEncoders.

src/preprocessing/series_encoder.rs

@@ -144,10 +144,9 @@ where
     pub fn invert_one_hot<U, V>(&self, one_hot: V) -> Result<C, Failed>
     where
         U: RealNumber,
-        V: BaseVector<U>
-
+        V: BaseVector<U>,
     {
-            let pos = U::from_f64(1f64).unwrap();
+        let pos = U::one();
 
         let oh_it = (0..one_hot.len()).map(|idx| one_hot.get(idx));
 
@@ -158,7 +157,7 @@ where
 
         if s.len() == 1 {
             let idx = s[0];
-                return Ok(self.mapper.get_cat(idx).clone());
+            return Ok(self.get_cat(idx).clone());
         }
         let pos_entries = format!(
             "Expected a single positive entry, {} entires found",
@@ -167,17 +166,35 @@ where
         Err(Failed::transform(&pos_entries[..]))
     }
 
-    fn transform_one<U, V>(&self, category: &C) -> Option<V> 
+    /// Get ordinal encoding of the catergory
+    pub fn get_ordinal<U>(&self, category: &C) -> Option<U>
     where
         U: RealNumber,
-        V: BaseVector<U>
     {
-        match self.mapper.get_num(category) {
+        match self.get_num(category) {
             None => None,
-            Some(&idx) => Some(make_one_hot(idx, self.num_categories())),
+            Some(&idx) => U::from_usize(idx),
+        }
     }
 }
 
+/// Make a one-hot encoded vector from a categorical variable
+///
+/// Example:
+/// ```
+/// use smartcore::preprocessing::series_encoder::make_one_hot;
+/// let one_hot: Vec<f64> = make_one_hot(2, 3);
+/// assert_eq!(one_hot, vec![0.0, 0.0, 1.0]);
+/// ```
+pub fn make_one_hot<T, V>(category_idx: usize, num_categories: usize) -> V
+where
+    T: RealNumber,
+    V: BaseVector<T>,
+{
+    let pos = T::one();
+    let mut z = V::zeros(num_categories);
+    z.set(category_idx, pos);
+    z
 }
 
 #[cfg(test)]
@@ -188,8 +205,8 @@ mod tests {
     fn from_categories() {
         let fake_categories: Vec<usize> = vec![1, 2, 3, 4, 5, 3, 5, 3, 1, 2, 4];
         let it = fake_categories.iter().map(|&a| a);
-        let enc = SeriesOneHotEncoder::<usize>::fit_to_iter(it);
-        let oh_vec: Vec<f64> = match enc.transform_one(&1) {
+        let enc = CategoryMapper::<usize>::fit_to_iter(it);
+        let oh_vec: Vec<f64> = match enc.get_one_hot(&1) {
             None => panic!("Wrong categories"),
             Some(v) => v,
         };
@@ -197,19 +214,24 @@ mod tests {
         assert_eq!(oh_vec, res);
     }
 
-    fn build_fake_str_enc<'a>() -> SeriesOneHotEncoder<&'a str> {
+    fn build_fake_str_enc<'a>() -> CategoryMapper<&'a str> {
         let fake_category_pos = vec!["background", "dog", "cat"];
-        let enc = SeriesOneHotEncoder::<&str>::new( CategoryMapper::from_positional_category_vec(fake_category_pos));
+        let enc = CategoryMapper::<&str>::from_positional_category_vec(fake_category_pos);
         enc
     }
+    #[test]
+    fn ordinal_encoding() {
+        let enc = build_fake_str_enc();
+        assert_eq!(1f64, enc.get_ordinal::<f64>(&"dog").unwrap())
+    }
 
     #[test]
     fn category_map_and_vec() {
         let category_map: HashMap<&str, usize> = vec![("background", 0), ("dog", 1), ("cat", 2)]
             .into_iter()
             .collect();
-        let enc = SeriesOneHotEncoder::<&str>::new( CategoryMapper::from_category_map(category_map));
-        let oh_vec: Vec<f64> = match enc.transform_one(&"dog") {
+        let enc = CategoryMapper::<&str>::from_category_map(category_map);
+        let oh_vec: Vec<f64> = match enc.get_one_hot(&"dog") {
             None => panic!("Wrong categories"),
             Some(v) => v,
         };
@@ -220,7 +242,7 @@ mod tests {
     #[test]
     fn positional_categories_vec() {
         let enc = build_fake_str_enc();
-        let oh_vec: Vec<f64> = match enc.transform_one(&"dog") {
+        let oh_vec: Vec<f64> = match enc.get_one_hot(&"dog") {
             None => panic!("Wrong categories"),
             Some(v) => v,
         };
@@ -232,9 +254,9 @@ mod tests {
     fn invert_label_test() {
         let enc = build_fake_str_enc();
         let res: Vec<f64> = vec![0.0, 1.0, 0.0];
-        let lab = enc.invert_one(res).unwrap();
+        let lab = enc.invert_one_hot(res).unwrap();
         assert_eq!(lab, "dog");
-        if let Err(e) = enc.invert_one(vec![0.0, 0.0, 0.0]) {
+        if let Err(e) = enc.invert_one_hot(vec![0.0, 0.0, 0.0]) {
             let pos_entries = format!("Expected a single positive entry, 0 entires found");
             assert_eq!(e, Failed::transform(&pos_entries[..]));
         };
@@ -244,7 +266,7 @@ mod tests {
     fn test_many_categorys() {
         let enc = build_fake_str_enc();
         let cat_it = ["dog", "cat", "fish", "background"].iter().cloned();
-        let res: Vec<Option<Vec<f64>>> = enc.transform_iter(cat_it);
+        let res: Vec<Option<Vec<f64>>> = cat_it.map(|v| enc.get_one_hot(&v)).collect();
         let v = vec![
             Some(vec![0.0, 1.0, 0.0]),
             Some(vec![0.0, 0.0, 1.0]),