corgi 0.9.7

Machine learning, and automatic differentation implementation for Rust
Documentation

Examples

  • For fully-connected examples, remember to call model.update().
  • Fully-connected MNIST (convolutional neural networks are in-progress).
  • Fully-connected neural network (full version):
let initializer = initializer::make_he();
let relu = activation::make_relu();
let softmax = activation::make_softmax();
let ce = cost::make_cross_entropy();
let gd = GradientDescent::new(learning_rate);
let l1 = Dense::new(input_size, hidden_size, initializer.clone(), Some(relu));
let l2 = Dense::new(hidden_size, output_size, initializer.clone(), Some(softmax));
let mut model = Model::new(vec![Box::new(l1), Box::new(l2)], Box::new(gd), ce);

for _ in 0..iterations {
    let mut input = vec![0.0; input_size * batch_size];
    let mut target = vec![0.0; output_size * batch_size];

    // set inputs, and targets

    // arrays in corgi should not be mutated after creation, so we initialise the values first
    let input = Array::from((vec![batch_size, input_size], input));
    let target = Array::from((vec![batch_size, output_size], target));

    let _result = model.forward(input.clone());
    let loss = model.backward(target.clone());
    // update the parameters, and clear gradients (backward pass only sets gradients)
    model.update();

    println!("loss: {}", loss);
}
  • Dynamic computational graph:
let a = arr![5.0].tracked();
let b = arr![2.0].tracked();
let mut c = arr![0.0].tracked();

for _ in 0..10 {
    c = &c + &(&a * &b);
    if c[0] > 50.0 {
        c = &c * &a;
    }
}

assert_eq!(c, arr![195300.0]);

c.backward(None);
assert_eq!(c.gradient(), arr![1.0]);
assert_eq!(b.gradient(), arr![97650.0]);
assert_eq!(a.gradient(), arr![232420.0]);

Important Design Notes

  • Array values should never be modified from operations; instead, new arrays should be created.
  • Arrays are untracked by default, so if gradients are required, tracked(), or start_tracking() must be used (see the documentation for details).
  • Versions prior to 0.9.7 of Corgi did not prioritise optimisation, and will be slow.

Design

  • Eager execution.
  • Dynamic-as-possible computational graph.
  • Originally worked around the ergonomics of the arr! macro (which however, currently still needs more work).
  • Did not want to have to manage any 'graph' structures when using Corgi (the Arrays should represent the graph alone).
  • Graphs do note store consumers (at the moment). They store consumer counts instead.

BLAS

  • The opeblas, or netlib features can be enabled, and requires CBLAS if used.

Tracked Arrays

  • Tracked arrays are arrays which require gradients to be computed, and stored.
  • For more information, see the documentation for tracked(), and untracked() in array.rs.

Name

  • Original name was going to be 'cog-(something)', since Rust's logo is a cog, and since cognition (get it?). But, many AI libraries are named 'cog-(something)'. Attempts at permutations of 'cog' with other words sounded awkward, such as 'cogi', for 'cog-intelligence', so the name Corgi was chosen.

Resources

  • Shields are from shields.io.
  • MIT 6.034 on OpenCourseWare for a primer on Backward Propagation.
  • CS231n YouTube recordings for a primer on Convolutional Neural Networks.

A lot of the library was built around being as dynamic as possible, meaning if chosen well, some design choices might be similar to other dynamic computational graph libraries.

Licence

  • MIT