cannot move out of index of `Vec<Layer>` - machine-learning

Question

use fastapprox::faster::sigmoid;
pub struct Neuron {
pub val: f32,
pub con: Vec<f32>
}
impl Neuron {
fn new(nextlaylen: u32) -> Neuron {
let mut con = Vec::new();
for _ in 0..nextlaylen {
con.push(0.0);
}
Neuron { val: 0.0, con: con }
}
pub fn add(&self, layer: &mut Layer) {
// loop through neurons and add values with weights
let mut counter = 0;
for i in 0..layer.neurons.len() {
counter += 1;
layer.neurons[i].val += self.val * self.con[counter];
}
}
}
pub struct Layer {
pub neurons: Vec<Neuron>
}
impl Layer {
pub fn new(size: u32, nextlaylen: u32) -> Layer {
let mut neurons = Vec::new();
for _ in 0..size {
neurons.push(Neuron::new(nextlaylen));
}
Layer { neurons: neurons }
}
pub fn add(self, layer: &mut Layer) {
// add neurons together
for i in 0..self.neurons.len() {
self.neurons[i].add(layer);
}
for i in 0..layer.neurons.len() {
layer.neurons[i].val = sigmoid(layer.neurons[i].val);
}
}
}
pub struct Model {
pub layers: Vec<Layer>
}
impl Model {
pub fn new(inputnodesamnt: u32, outputnodesamnt: u32, hiddenlayersamnt: u32, neuronsperlayer: u32) -> Model {
let mut layers = Vec::new();
layers.push(Layer::new(inputnodesamnt, neuronsperlayer)); // create input layer
// create hidden layers
for i in 0..hiddenlayersamnt {
if i != hiddenlayersamnt - 1 {
layers.push(Layer::new(neuronsperlayer, neuronsperlayer));
}
else {
layers.push(Layer::new(neuronsperlayer, outputnodesamnt));
}
}
layers.push(Layer::new(outputnodesamnt, 0)); // create output layer
Model { layers: layers }
}
pub fn process(self) {
for i in 0..self.layers.len() {
self.layers[i].add(&mut self.layers[i + 1]);
}
}
}
pub struct Output {
pub nodevaluearr: Vec<f32>
}
fn main() {
}
the error I get is this:
error[E0507]: cannot move out of index of `Vec<Layer>`
--> src/main.rs:83:13
|
83| self.layers[i].add(&mut self.layers[i + 1]);
| ^^^^^^^^^^^^^^ move occurs because value has type `Layer`, which does not implement the `Copy` trait
For more information about this error, try `rustc --explain E0507`.
error: could not compile `neuralnetrust` due to previous error
The terminal process "cargo 'run', '--package', 'neuralnetrust', '--bin', 'neuralnetrust'" failed to launch (exit code: 101).
I'm trying to make a simple neural net.
also, does anybody have any good resources for learning about the borrow checker?

Answer 1

Your add method takes ownership of self, when in reality you probably want to take &self. When you have a function which takes self instead of &self or &mut self, then when you call it on an object that object gets passed into the function and you cannot access it again (assuming it's not Copy) after that since Rust has move semantics by default. If you want to learn more about Rust's memory model then I'd spend some time with this chapter of the book.