A GPU accelerated library that creates/trains/runs neural networks in safe Rust code.

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Table of contents

• Architecture overview
  • Models
  • Layers
  • Optimizers
  • Loss Functions
• XoR using Intricate
  • Setting up the training data
  • Setting up the layers
  • Setting up OpenCL
  • Fitting our Model
• How to save and load models
  • Saving the Model
  • Loading the Model
• Things to be done still

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Architecture overview

Intricate has a layout very similar to popular libraries out there such as Keras.

It consists at the surface of a Model, which consists then of Layers which can be adjusted using a Loss Function that is also helped by an Optimizer.

Models

As said before, similar to Keras, Intricate defines Models as basically a list of Layers.

A model does not have much logic in it, mostly it delegates most of the work to the layers, all that it does is orchestrate how the layers should work together and how the data goes from a layer to another.

Layers

Every layer receives inputs and returns outputs following some rule that they must define.

They must also implement four methods that together constitute back-propagation:

• optimize_parameters
• compute_gradients
• apply_gradients
• compute_loss_to_input_derivatives

Mostly the optimize_parameters will rely on an Optimizer that will try to improve the parameters that the Layer allows it to optimize.

These methods together will be called sequentially to do back-propagation in the Model and using the results from the compute_loss_to_input_derivatives we will then do the same for the last layer and so on.

These layers can be really any type of transformation on the inputs and outputs. An example of this is the activation functions in Intricate which are actual layers instead of being one with other layers which does simplify calculations tremendously and works like a charm.

Optimizers

Optimizers the do just what you might think, they optimize.

Specifically they optimize both the parameters a Layer allows them to optimize, and the Layer's gradients so that the Layer can use them to apply the optimized gradients on itself.

This is useful because one using Intricate can develop, and perhaps debug, an Optimizer to see how well it does for certain use cases which is very good for where I want Intricate to go. All you have to do is create some struct that implements the Optimizer trait.

Loss Functions

Loss Functions are just basically some implementations of a certain trait that are used to determine how bad a Model is.

Loss Functions are NOT used in a layer, they are used for the Model itself. Even though a Layer will use derivatives with respect to the loss they don't really communicate with the Loss Function directly.

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XoR using Intricate

If you look at the examples/ in the repository you will find XoR implemented using Intricate. The following is basically just that example with some separate explanation.

Setting up the training data

let training_inputs = vec![
    vec![0.0, 0.0],
    vec![0.0, 1.0],
    vec![1.0, 0.0],
    vec![1.0, 1.0],
];

let expected_outputs = vec![
    vec![0.0],
    vec![1.0],
    vec![1.0],
    vec![0.0],
];

Setting up the layers

use intricate::layers::{
    activations::TanH,
    Dense
};
let mut layers: Vec<ModelLayer> = vec![
    Dense::new(2, 3), // inputs amount, outputs amount
    TanH::new (3),
    Dense::new(3, 1),
    TanH::new (1),
];

Creating the model with the layers

use intricate::Model;
// Instantiate our model using the layers
let mut xor_model = Model::new(layers);

We make the model mut because we will call fit for training our model which will tune each of the layers when necessary.

Setting up OpenCL's state

Since Intricate does use OpenCL under the hood for doing calculations, we do need to initialize a OpenCLState which is just a struct containing some necessary OpenCL stuff:

use intricate::utils::{
    setup_opencl,
    DeviceType
}
//              you can change this device type to GPU if you want
let opencl_state = setup_opencl(DeviceType::CPU).unwrap();

For our Model to be able to actually do computations, we need to pass the OpenCL state into the init method inside the Model as follows:

xor_model.init(&opencl_state).unwrap();

Fitting our model

For training our Model we just need to call the fit method and pass in some parameters as follows:

use intricate::{
    loss_functions::MeanSquared,
    optimizers,
    types::{TrainingOptions, TrainingVerbosity},
};

let mut loss = MeanSquared::new(); // the type of loss function that should be used for Intricate
                                   // to determine how bad the Model is
let mut optimizer = optimizers::Basic::new(0.1); // the optimizer tries to use the gradients to optimize the training
                                                 // process

// Fit the model however many times we want
xor_model
    .fit(
        &training_inputs,
        &expected_outputs,
        &mut TrainingOptions::new(&mut loss, &mut optimizer)
            .set_epochs(10000)
            .set_batch_size(4) // the size of the mini-batch being used in Intricate's Mini-batch
                               // Gradient Descent
            .should_compute_accuracy(true).unwrap() // if Intricate should compute the accuracy after each
                                                    // training step
            .should_print_accuracy(true).unwrap() // should print the accuracy after each epoch
            //                 a condition for stopping the training if a min accuracy is reached
            .set_halting_condition(HaltingCondition::MinAccuracyReached(0.95)).unwrap()
            .should_show_halting_condition_warning(true).unwrap(),
    )
    .unwrap();

As you can see it is extremely easy creating these models, and blazingly fast as well.

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How to save and load models

For saving and loading models Intricate uses the savefile crate which makes it very simple and fast to save models.

Saving the model

As an example let's try saving and loading our XoR model.

For doing that we will first need to sync all the relevant layer information of the Model with OpenCL's host, (or just with the CPU), and then we will need to call the save_file method as follows:

xor_model.sync_data_from_buffers_to_host().unwrap(); // sends the weights and biases from 
                                                     // OpenCL buffers to Rust Vec's
save_file("xor-model.bin", 0, &xor_model).unwrap();

Loading the model

As for loading our XoR model, we just need to call the counterpart of the save_file method: load_file.

let mut loaded_xor_model: Model = load_file("xor-model.bin", 0).unwrap();

Now of curse, the savefile crate cannot load in the data to the GPU, so if you want to use the Model after loading it, you must call the init method in the loaded_xor_model (done in examples/xor.rs).

Things to be done still

• implement Max Pooling or other Pooling type of layers;
• add a way to send into the training process a callback closure that would be called every time an epoch finished or even a step too with some cool info;
• make an example after doing the thing above ^, that uses that same function to plot the loss real time using a crate like textplots;
• add embedding layers for text such as bag of words with an expected vocabulary size;
• add a way to show inputs and outputs not matching error be more clear and perhaps even appear at compile time;
• add a way to choose what type of accuracy should be calculated to avoid weird and unuseful accuracies being calculated
• make Intricate GPU parallel (gonna take a long time to implement and can't do it rn since I don't have multiple GPUs available to me)
• add a way to epxose Intricate's used crates such as SaveFile and OpenCL3 to be used outside by a user if needed without having to install them