It doesn't work

src/learner.rs

@@ -35,8 +35,21 @@ impl Learner {
         }
         self.best_algorithm.clone()
     }
+    pub fn calculate_formula_debug(&mut self) -> Formula {
+        for _ in 0..self.iterations {
+            self.best_algorithm = self.iterate();
+            self.best_algorithm.display_tree();
+        }
+        self.best_algorithm.clone()
+    }
     fn iterate(&self) -> Formula {
-        let mut formulas: Vec<(Formula, f64)> = vec![];
+        let best_similarity = Learner::get_similarity(
+            &self.expected_outputs,
+            &self.best_algorithm.run(self.inputs.clone()),
+        )
+        .unwrap();
+        let mut formulas: Vec<(Formula, f64)> =
+            vec![(self.best_algorithm.clone(), best_similarity)];
         for _ in 0..self.formulas_per_iteration {
             let mut formula = self.best_algorithm.clone();
             Learner::mutate_formula_randomly(&mut formula);
@@ -63,7 +76,7 @@ impl Learner {
     }
     fn mutate_formula_randomly(formula: &mut Formula) {
         let mut editor = formula.modify_random_node();
-        let decided_action = random_range(0..3);
+        let decided_action = random_range(0..4);
         if decided_action == ACTION_ADD {
             editor.add_node(editor.get_random_node());
         } else if decided_action == ACTION_REMOVE {

src/main.rs

@@ -8,9 +8,11 @@ mod tests;
 fn main() {
     let mut learner = Learner::new(
         vec![0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 10.],
-        vec![1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11.],
-        None,
+        vec![0., 2., 4., 6., 8., 10., 12., 14., 16., 19., 20.],
         None,
+        Some(10000),
     );
-    println!("{:?}", learner.calculate_formula().as_text());
+    let formula = learner.calculate_formula();
+    println!("{:?}", formula.as_text());
+    formula.display_tree();
 }

src/node/mod.rs

@@ -29,7 +29,7 @@ impl Node {
         Self {
             children: vec![],
             handler: NodeHandler::Empty,
-            max_children_count: None,
+            max_children_count: Some(1),
         }
     }
     pub fn number(n: f64) -> Self {
@@ -74,6 +74,33 @@ impl Node {
 
         return self.handler.run(inputs, passed_x);
     }
+    pub fn set_handler(&mut self, to: NodeHandler) {
+        match &to {
+            NodeHandler::Number { number } => {
+                self.max_children_count = Some(0);
+                self.children.clear();
+            }
+            NodeHandler::Function {
+                name,
+                function,
+                max_args,
+                min_args,
+            } => {
+                self.max_children_count = max_args.clone();
+                if let Some(x) = max_args {
+                    self.children.truncate(x.clone());
+                }
+            }
+            NodeHandler::Variable => {
+                self.max_children_count = Some(0);
+                self.children.clear();
+            }
+            NodeHandler::Empty => {
+                self.max_children_count = Some(1);
+                self.children.truncate(1);
+            }
+        }
+    }
     pub fn modify_node(&mut self) -> NodeModifier {
         NodeModifier::from_random(self, None)
     }

src/node/node_modifier/mod.rs

@@ -6,7 +6,7 @@ use rand::random_range;
 pub mod errors;
 
 const PICK_STOP_PROBABILITY: u8 = 2;
-const TYPE_CHANGE_PROBABILITY: u8 = 10;
+const TYPE_CHANGE_PROBABILITY: u8 = 2;
 
 pub struct NodeModifier<'a> {
     picked_node: &'a mut Node,
@@ -120,6 +120,9 @@ impl<'a> NodeModifier<'a> {
         &mut self,
         specified_index: Option<usize>,
     ) -> Result<(), NodeManipulationError> {
+        if let NodeHandler::Empty = &self.picked_node.handler {
+            return Err(NodeManipulationError::ProtectedEmpty);
+        }
         if self.picked_node.children.len() == 0 {
             return Err(NodeManipulationError::NotEnoughChildren);
         }
@@ -149,6 +152,11 @@ impl<'a> NodeModifier<'a> {
             }
         }
         let children_count = self.picked_node.children.len();
+        if let NodeHandler::Empty = &self.picked_node.handler
+            && children_count - 1 > 0
+        {
+            return Err(NodeManipulationError::TooMuchChildren(node));
+        }
         if children_count <= 0 {
             return Err(NodeManipulationError::NotEnoughChildren);
         }
@@ -166,12 +174,12 @@ impl<'a> NodeModifier<'a> {
         } else {
             match &self.picked_node.handler {
                 NodeHandler::Number { number } => {
-                    self.picked_node.handler = NodeHandler::Number {
+                    self.picked_node.set_handler(NodeHandler::Number {
                         number: (self.number_mutation_pool
                             [random_range(0..self.number_mutation_pool.len())])(
                             number.clone()
                         ),
-                    };
+                    });
                 }
                 NodeHandler::Function {
                     function,
@@ -181,23 +189,18 @@ impl<'a> NodeModifier<'a> {
                 } => {
                     let selected_mutation = &self.function_mutation_pool
                         [random_range(0..self.function_mutation_pool.len())];
-                    if let NodeHandler::Function {
-                        name,
-                        function,
-                        max_args,
-                        min_args,
-                    } = &selected_mutation
-                    {
-                        self.picked_node.max_children_count = max_args.clone();
-                        self.picked_node.handler = selected_mutation.clone();
-                    }
+                    self.picked_node.set_handler(selected_mutation.clone());
                 }
                 _ => {}
             }
         }
     }
     pub fn change_node_type(&mut self, to: Option<NodeHandler>) {
-        self.picked_node.handler = to.unwrap_or(self.get_random_handler());
+        if let NodeHandler::Empty = &self.picked_node.handler {
+            return;
+        }
+        let next_type = to.unwrap_or(self.get_random_handler());
+        self.picked_node.set_handler(next_type);
     }
     pub fn get_random_handler(&self) -> NodeHandler {
         let picked = random_range(0..3);

src/tests.rs

@@ -1,4 +1,4 @@
-use crate::{formula::Formula, node::Node};
+use crate::{formula::Formula, learner::Learner, node::Node};
 
 #[test]
 fn test_node_variable() {
@@ -17,7 +17,8 @@ fn test_plus_one() {
                 Node::function(
                     "+1".to_string(),
                     |inputs: Vec<f64>| inputs[0] + 1f64,
-                    Some(1)
+                    Some(1),
+                    1
                 ),
                 None
             )
@@ -35,7 +36,7 @@ fn test_branch_sum() {
         formula
             .modify_tree()
             .insert_node(
-                Node::function("Sum".to_string(), |inputs| inputs.iter().sum(), Some(2)),
+                Node::function("Sum".to_string(), |inputs| inputs.iter().sum(), Some(2), 0),
                 None
             )
             .is_err()
@@ -60,7 +61,7 @@ fn test_display_as_text() {
         formula
             .modify_tree()
             .insert_node(
-                Node::function("sum".to_string(), |inputs| inputs.iter().sum(), None),
+                Node::function("sum".to_string(), |inputs| inputs.iter().sum(), None, 0),
                 None
             )
             .is_err()
@@ -73,7 +74,8 @@ fn test_display_as_text() {
             .add_node(Node::function(
                 "sin".to_string(),
                 |inputs| inputs[0].sin(),
-                Some(1)
+                Some(1),
+                0
             ))
             .is_err()
             == false
@@ -89,3 +91,12 @@ fn test_display_as_text() {
     );
     assert_eq!(formula.as_text(), "sum(X,sin(X))".to_string());
 }
+
+#[test]
+fn test_2x() {
+    let inputs = vec![0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12.];
+    let outputs = vec![0., 2., 4., 6., 8., 10., 12., 14., 16., 18., 20., 22., 24.];
+    let mut learner = Learner::new(inputs.clone(), outputs.clone(), None, None);
+    let formula = learner.calculate_formula();
+    assert_eq!(formula.run(inputs), outputs);
+}