commit c84187f44653918c42762e96ef3cc933fd0ba94b
Author: markichnich <markichnich@proton.me>
Date:   Fri Mar 8 16:52:45 2024 +0100

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..2186b8c
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,75 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aicaramba"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "190092ea657667030ac6a35e305e62fc4dd69fd98ac98631e5d3a2b1575a12b5"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.153"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..62bb089
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "aicaramba"
+version = "0.1.0"
+edition = "2021"
+license = "MIT"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rand = { version = "0.8.5", optional = true }
diff --git a/src/bin/xor.rs b/src/bin/xor.rs
new file mode 100644
index 0000000..e7cfb56
--- /dev/null
+++ b/src/bin/xor.rs
@@ -0,0 +1,18 @@
+use aicaramba::functions::*;
+use aicaramba::neural_net::NeuralNet;
+
+fn main() {
+    let mut net = NeuralNet::new(vec![2, 3, 1], SIGMOID, MSE, 0.05);
+    let epochs = 10_000;
+
+    let inputs = vec![
+        vec![0.0, 0.0],
+        vec![0.0, 1.0],
+        vec![1.0, 0.0],
+        vec![1.0, 1.0],
+    ];
+
+    let expected = vec![vec![0.0], vec![1.0], vec![1.0], vec![0.0]];
+
+    net.train_basic(inputs, expected, epochs);
+}
diff --git a/src/functions.rs b/src/functions.rs
new file mode 100644
index 0000000..3358431
--- /dev/null
+++ b/src/functions.rs
@@ -0,0 +1,29 @@
+use crate::matrix::MatElem;
+
+#[derive(Clone, Copy, Debug)]
+pub struct ActivationFn<T>
+where
+    T: MatElem,
+{
+    pub f: fn(T) -> T,
+    pub f_prime: fn(T) -> T,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct LossFn<T>
+where
+    T: MatElem,
+{
+    pub f: fn(T, T) -> T,
+    pub f_prime: fn(T, T) -> T,
+}
+
+pub const SIGMOID: ActivationFn<f64> = ActivationFn {
+    f: |x| 1.0 / (1.0 + f64::exp(-x)),
+    f_prime: |x| x * (1.0 - x),
+};
+
+pub const MSE: LossFn<f64> = LossFn {
+    f: |y_hat, y| (y_hat - y).powi(2),
+    f_prime: |y_hat, y| -2.0 * (y_hat - y),
+};
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..7c87e71
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,3 @@
+pub mod functions;
+pub mod matrix;
+pub mod neural_net;
diff --git a/src/matrix.rs b/src/matrix.rs
new file mode 100644
index 0000000..620b4bf
--- /dev/null
+++ b/src/matrix.rs
@@ -0,0 +1,300 @@
+use rand::Rng;
+use std::ops::{Add, Mul, Sub};
+
+// NOTE: might want to rethink design (to 2d-vec?) to enable `matrix[i][j]`
+// indexing and make nice row-iterator implementation possible
+#[derive(Debug, Clone)]
+pub struct Mat<T>
+where
+    T: MatElem,
+{
+    pub rows: usize,
+    pub cols: usize,
+    data: Vec<T>,
+}
+
+/// Shorthand/alias trait for types that are valid as matrix elements.
+pub trait MatElem:
+    PartialEq + Clone + Default + Add<Output = Self> + Sub<Output = Self> + Mul<Output = Self>
+{
+}
+
+impl<T> MatElem for T where
+    T: PartialEq + Clone + Default + Add<Output = T> + Sub<Output = T> + Mul<Output = T>
+{
+}
+
+impl<T> Mat<T>
+where
+    T: MatElem,
+{
+    pub fn new(rows: usize, cols: usize, data: Vec<T>) -> Mat<T> {
+        assert!(data.len() == rows * cols, "Invalid Size");
+        Mat { rows, cols, data }
+    }
+
+    pub fn at(&self, row: usize, col: usize) -> &T {
+        &self.data[row * self.cols + col]
+    }
+
+    pub fn at_mut(&mut self, row: usize, col: usize) -> &mut T {
+        &mut self.data[row * self.cols + col]
+    }
+
+    pub fn default_with_size(rows: usize, cols: usize) -> Mat<T> {
+        Mat {
+            rows,
+            cols,
+            data: vec![T::default(); cols * rows],
+        }
+    }
+
+    pub fn add(&self, other: &Mat<T>) -> Mat<T> {
+        if self.rows != other.rows || self.cols != other.cols {
+            panic!("Attempted to add matrices with differing shapes.");
+        }
+        self.elementwise(other, |a, b| a + b)
+    }
+
+    pub fn sub(&self, other: &Mat<T>) -> Mat<T>
+    where
+        T: std::ops::Sub<Output = T>,
+    {
+        if self.rows != other.rows || self.cols != other.cols {
+            panic!("Attempted to subtract matrices with differing shapes.");
+        }
+        self.elementwise(other, |a, b| a - b)
+    }
+
+    pub fn elementwise_mul(&self, other: &Mat<T>) -> Mat<T>
+    where
+        T: std::ops::Mul<Output = T>,
+    {
+        if self.rows != other.rows || self.cols != other.cols {
+            panic!("Attempted to elementwise-multiply matrices of differing shapes.");
+        }
+        self.elementwise(other, |a, b| a * b)
+    }
+
+    pub fn elementwise(&self, other: &Mat<T>, f: fn(T, T) -> T) -> Mat<T> {
+        if self.rows != other.rows || self.cols != other.cols {
+            panic!("Attempted to apply element-wise operation to matrices with differing shapes.");
+        }
+
+        let data = self
+            .data
+            .iter()
+            .zip(other.data.iter())
+            .map(|(a, b)| f(a.clone(), b.clone()))
+            .collect::<Vec<_>>();
+
+        Mat {
+            rows: self.rows,
+            cols: self.cols,
+            data,
+        }
+    }
+
+    pub fn dot(&self, other: &Mat<T>) -> Mat<T> {
+        if self.cols != other.rows {
+            panic!(
+                "Attempted to take dot product of incompatible matrix shapes. (A.cols != B.rows)"
+            );
+        }
+
+        let mut data = vec![T::default(); self.rows * other.cols];
+
+        for i in 0..self.rows {
+            for j in 0..other.cols {
+                let mut sum = T::default();
+                for k in 0..self.cols {
+                    sum = sum
+                        + self.data[i * self.cols + k].clone()
+                            * other.data[k * other.cols + j].clone();
+                }
+                data[i * other.cols + j] = sum;
+            }
+        }
+
+        Mat {
+            rows: self.rows,
+            cols: other.cols,
+            data,
+        }
+    }
+
+    pub fn transpose(&self) -> Mat<T> {
+        let mut buffer = vec![T::default(); self.cols * self.rows];
+
+        for i in 0..self.rows {
+            for j in 0..self.cols {
+                buffer[j * self.rows + i] = self.data[i * self.cols + j].clone();
+            }
+        }
+
+        Mat {
+            rows: self.cols,
+            cols: self.rows,
+            data: buffer,
+        }
+    }
+
+    pub fn map<F>(&self, f: F) -> Mat<T>
+        where F: FnMut(T) -> T
+    {
+        Mat {
+            rows: self.rows, cols: self.cols,
+            data: self.data.clone()
+                .into_iter()
+                .map(f)
+                .collect()
+        }
+    }
+}
+
+pub trait Collect<T>
+    where T: MatElem,
+{
+    fn collect_mat(self, rows: usize, cols: usize) -> Mat<T>;
+}
+
+impl<T> Collect<T> for T
+where T: MatElem + std::iter::IntoIterator<Item = T>
+{
+    fn collect_mat(self, rows: usize, cols: usize) -> Mat<T> {
+        let data = self.into_iter().collect::<Vec<T>>();
+        if data.len() != rows * cols {
+            panic!("Collecting iterator into matrix failed due to incompatible matrix shape.")
+        }
+        Mat { rows, cols, data }
+    }
+}
+
+// the random function is only available if `rand` supports randomizing the element type
+impl<T> Mat<T>
+where
+    T: MatElem,
+    rand::distributions::Standard: rand::distributions::Distribution<T>,
+{
+    // TODO: depend on randomization feature
+    pub fn random(rows: usize, cols: usize) -> Mat<T> {
+        let mut data = Vec::with_capacity(rows * cols);
+
+        for _ in 0..rows * cols {
+            data.push(rand::thread_rng().gen());
+        }
+
+        Mat { rows, cols, data }
+    }
+}
+
+// NOTE: might want to change this to two row- and col-iters in the future
+//       then might implement something like `flat_iter` that mirrors
+//       current behavior.
+impl<T> IntoIterator for Mat<T>
+where
+    T: MatElem,
+{
+    type Item = T;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.data.into_iter()
+    }
+}
+
+impl<T> From<Vec<T>> for Mat<T>
+where
+    T: MatElem,
+{
+    fn from(value: Vec<T>) -> Self {
+        let rows = value.len();
+        let cols = 1;
+        Mat {
+            rows,
+            cols,
+            data: value,
+        }
+    }
+}
+
+impl<T> From<Vec<Vec<T>>> for Mat<T>
+where
+    T: MatElem,
+{
+    fn from(value: Vec<Vec<T>>) -> Self {
+        let rows = value.len();
+        let cols = value.first().map(Vec::len).unwrap_or(0);
+        Mat {
+            rows,
+            cols,
+            data: value.into_iter().flatten().collect(),
+        }
+    }
+}
+
+impl<T> PartialEq for Mat<T>
+where
+    T: MatElem,
+{
+    fn eq(&self, other: &Self) -> bool {
+        self.rows == other.rows && self.cols == other.cols && self.data == other.data
+    }
+}
+
+impl<T> std::ops::Index<usize> for Mat<T>
+where
+    T: MatElem,
+{
+    type Output = [T];
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.data[index * self.cols..(index + 1) * self.cols]
+    }
+}
+
+impl<T> std::fmt::Display for Mat<T>
+where
+    T: MatElem + std::fmt::Display,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for row in 0..self.rows {
+            for col in 0..self.cols {
+                write!(f, "{}", self.data[row * self.cols + col])?;
+                if col < self.cols - 1 {
+                    write!(f, "\t")?;
+                }
+            }
+            writeln!(f)?;
+        }
+        Ok(())
+    }
+}
+
+#[macro_export]
+macro_rules! matrix {
+    ( $( $($val:expr),+ );* $(;)? ) => {
+        {
+            let mut data = Vec::<f64>::new();
+            let mut rows = 0;
+            let mut cols = 0;
+            $(
+                let row_data = vec![$($val),+];
+                data.extend(row_data);
+                rows += 1;
+                let row_len = vec![$($val),+].len();
+                if cols == 0 {
+                    cols = row_len;
+                } else if cols != row_len {
+                    panic!("Inconsistent number of elements in the matrix rows");
+                }
+            )*
+
+            Mat {
+                rows,
+                cols,
+                data,
+            }
+        }
+    };
+}
diff --git a/src/neural_net.rs b/src/neural_net.rs
new file mode 100644
index 0000000..e74bf07
--- /dev/null
+++ b/src/neural_net.rs
@@ -0,0 +1,135 @@
+use crate::functions::*;
+use crate::matrix::{Mat, MatElem};
+
+/// Contains the following values:
+/// - `architecture: Vec<usize>`: The node counts for each layer (eg. `vec![2, 3, 1]`)
+/// - `weights: Vec<Mat>`: The weight matrices between two layers.
+/// - `biases: Vec<Mat>`: The bias matrices of the layers.
+/// - `learning_rate: f64`: The scalar learning rate.
+/// - `activation: ActivationFn`: Struct containing activation function and derivative
+/// - `loss: LossFn`: Struct containing loss function and derivative
+/// - `data: Vec<Mat>`: A buffer for the activated values during forward- and backward pass.
+pub struct NeuralNet<T>
+where
+    T: MatElem,
+{
+    architecture: Vec<usize>,
+    weights: Vec<Mat<T>>,
+    biases: Vec<Mat<T>>,
+
+    learning_rate: T,
+
+    activation: ActivationFn<T>,
+    loss: LossFn<T>,
+
+    data: Vec<Mat<T>>,
+}
+
+impl<T> NeuralNet<T>
+where
+    T: MatElem,
+    rand::distributions::Standard: rand::distributions::Distribution<T>,
+{
+    pub fn new(
+        layers: Vec<usize>,
+        activation: ActivationFn<T>,
+        loss: LossFn<T>,
+        learning_rate: T,
+    ) -> Self {
+        let mut weights = vec![];
+
+        let mut biases = vec![];
+
+        for i in 0..layers.len() - 1 {
+            weights.push(Mat::random(layers[i + 1], layers[i]));
+            biases.push(Mat::random(layers[i + 1], 1));
+        }
+
+        NeuralNet {
+            architecture: layers,
+            weights,
+            biases,
+            data: vec![],
+            activation,
+            loss,
+            learning_rate,
+        }
+    }
+}
+
+impl<T> NeuralNet<T>
+where
+    T: MatElem,
+{
+    pub fn forward(&mut self, inputs: Mat<T>) -> Mat<T> {
+        if self.architecture[0] != inputs.rows {
+            panic!("Input vector does not have correct number of rows.")
+        }
+
+        let mut current = inputs;
+        self.data = vec![current.clone()];
+
+        for i in 0..self.architecture.len() - 1 {
+            current = self.weights[i]
+                .dot(&current)
+                .add(&self.biases[i])
+                .map(self.activation.f);
+
+            self.data.push(current.clone());
+        }
+
+        current
+    }
+
+    pub fn backprop(&mut self, prediction: Mat<T>, truth: Mat<T>) {
+        let mut losses = prediction.elementwise(&truth, self.loss.f_prime);
+        let mut gradients = prediction.clone().map(self.activation.f_prime);
+
+        for i in (0..self.architecture.len() - 1).rev() {
+            gradients = gradients
+                .elementwise_mul(&losses)
+                .map(|x| x * self.learning_rate.clone());
+
+            self.weights[i] = self.weights[i].add(&gradients.dot(&self.data[i].transpose()));
+            self.biases[i] = self.biases[i].add(&gradients);
+
+            losses = self.weights[i].transpose().dot(&losses);
+            gradients = self.data[i].map(self.activation.f_prime);
+        }
+    }
+
+    // TODO: add batch-wise training
+    // TODO: refactor to use matrices instead of 2d-vecs
+    pub fn train_basic(&mut self, inputs: Vec<Vec<T>>, truth: Vec<Vec<T>>, epochs: u32)
+    where
+        T: std::fmt::Display,
+    {
+        let width = epochs.ilog10() as usize + 1;
+
+        for i in 1..=epochs {
+            let mut outputs: Mat<T>;
+            for j in 0..inputs.len() {
+                outputs = self.forward(Mat::from(inputs[j].clone()));
+                self.backprop(outputs, Mat::from(truth[j].clone()));
+            }
+
+            if epochs < 20 || i % (epochs / 20) == 0 {
+                let mut loss = T::default();
+                for j in 0..inputs.len() {
+                    outputs = self.forward(Mat::from(inputs[j].clone()));
+                    loss = loss
+                        + outputs
+                            .into_iter()
+                            .zip(&truth[j])
+                            .fold(T::default(), |sum, (y_hat, y)| {
+                                sum + (self.loss.f)(y_hat, y.clone())
+                            });
+                }
+                println!(
+                    "epoch: {i:0>width$} / {epochs:0>width$} ;\tloss: {:.5}",
+                    loss
+                );
+            }
+        }
+    }
+}