#neural-network #machine-learning #data-science #data-analysis #gradient-descent

bin+lib jiro_nn

Neural Networks framework with model building & data preprocessing features

6 releases (3 breaking)

0.8.1 Jul 10, 2023
0.8.0 Jul 10, 2023
0.7.1 Jul 9, 2023
0.6.0 Jul 8, 2023
0.5.0 Jul 4, 2023

#67 in Machine learning

24 downloads per month




Low-friction high-detail Deep Learning framework in Rust


Installation & cargo features

Add this in your project's Cargo.toml file, by replacing <BACKEND> with the backend you want to use (see Backends):

jiro_nn = { 
    version = "*", 
    default-features = false, 
    features = ["<BACKEND>", "data"] # "data" is optional and enables the preprocessing and dataframes features
feature description compile-time cost
data (default feature) adds DataTable, a simpler API for polars dataframes ; enables Kfolds training ; adds the preprocessing module for creating pipelines depending on dataset configurations High
parquet adds Apache Parquet files support for eveything related to the data feature Medium
ipc adds Arrow files support for eveything related to the data feature Medium
ndarray (default feature) changes the Matrix and Image types to a CPU-bound backend powered by the ndarray crate. Image and convolution operations are not fully implemented with this backend, But it's in the works. Low
nalgebra changes the Matrix and Image types to a CPU-bound backend powered by the nalgebra crate. Image and convolution operations are not fully implemented with this backend, and probably won't ever be. Low
arrayfire changes the Matrix and Image types to a GPU and CPU backend powered by the arrayfire crate. Ideal for Convolutional Networks. Requires the ArrayFire C++ library. See Installing Arrayfire Low, but hard to install
f64 changes the Scalar type from being backed by f32 to being backed by f64 None

Bare-bones XOR example

Predicting the XOR function with a simple neural network:

let x = vec![
    vec![0.0, 0.0],
    vec![1.0, 0.0],
    vec![0.0, 1.0],
    vec![1.0, 1.0],

let y = vec![

let network_model = NetworkModelBuilder::new()

let in_size = 2;
let mut network = network_model.to_network(in_size);
let loss = Losses::MSE.to_loss();

for epoch in 0..1000 {
    let error = network.train(epoch, &x, &y, &loss, 1);
    println!("Epoch: {} Error: {}", epoch, error);

Preprocessing + CNNs example

MNIST (hand-written digits recognition) workflow example:

// Step 1: Enrich the features of your data (eg. the "columns") with metadata using a Dataset configuration
// The configuration is necessary for guiding further steps (preprocessing, training...)

// Extract features from a spreadsheet to start building a dataset configuration
// You could also start blank and add the columns and metadata manually
let mut dataset_config = Dataset::from_file("dataset/train.csv");
// Now we can add metadata to our features
    // Flag useless features for removal
    // Tell the framework which column is an ID (so it can be ignored in training, used in joins, and so on)
    .tag_feature("id", IsId)
    // Tell the framework which column is the feature to predict
    // You could very well declare multiple features as Predicted
    .tag_feature("label", Predicted)
    // Since it is a classification problem, indicate the label needs One-Hot encoding during preprocessing
    .tag_feature("label", OneHotEncode)
    // You may also want to normalize everything except the ID & label during preprocessing
    .tag_all(Normalized.except(&["id", "label"]));

// Step 2: Preprocess the data

// Create a pipeline with all the necessary steps
let mut pipeline = Pipeline::basic_single_pass();
// Run it on the data
let (dataset_config, data) = pipeline
    .load_data("dataset/train.csv", Some(dataset_config))

// Step 3: Specify and build your model

// A model is tied to a dataset configuration
let model = ModelBuilder::new(dataset_config)
    // Some configuration is also tied to the model
    // All the configuration calls are optional, defaults are picked otherwise
    // Then you can start building the neural network
        // Specify all your layers
        // A convolution network is considered a layer of a neural network in this framework
            // Now the convolution layers
            .full_dense(32, 5)
                // You can set the activation function for any layer and many other parameters
                // Otherwise defaults are picked
            .full_dense(64, 5)
        // Now we go back to configuring the top-level neural network

    "Model parameters count: {}",

// Step 4: Train the model

// Monitor the progress of the training on a nice TUI (with other options coming soon)
// Use a SplitTraining to split the data into a training and validation set (k-fold also available)
let mut training = SplitTraining::new(0.8);
let (preds_and_ids, model_eval) = training.run(&model, &data);

// Step 5: Save the resulting predictions, weights and model evaluation

// Save the model evaluation per epoch

// Save the weights
let model_params = training.take_model();

// Save the predictions alongside the original data
let preds_and_ids = pipeline.revert(&preds_and_ids);
    .inner_join(&preds_and_ids, "id", "id", Some("pred"))

You can then plot the results using a third-party crate like gnuplot (recommended), plotly (also recommended) or even plotters.

For more in-depth examples, with more configurable workflows spanning many scripts, check out the examples folder.


Since it is a framework, it is quite opinionated and has a lot of features. But here are the main ones:

NNs (Dense Layers, Full Layers...), CNNs (Dense Layers, Direct Layers, Mean Pooling...), everything batched, SGD, Adam, Momentum, Glorot, many activations (Softmax, Tanh, ReLU...), Learning Rate Scheduling, K-Folds, Split training, cacheable and revertable Pipelines (normalization, feature extraction, outliers filtering, values mapping, one-hot-encoding, log scaling...), loss functions (Binary Cross Entropy, Mean Squared Errors), model building as code, preprocessing configuration as code, performance metrics (R²...), tasks monitoring (progress, logging), multi-backends (CPU, GPU, see Backends), multi-precision (see Precision).

Scope and goals

Main goals:

  • Implement enough algorithms so that it can fit most use-cases
  • Don't stop at NNs, also implement CNNs, RNNs, and whatever we can
  • Handle side use-cases that could also be considered "backend" (model building, training, preprocessing)
  • Craft opinionated APIs for the core features, and wrappers for useful support libraries if they are not simple enough (DataFrames, Linear Algebra...)
  • APIs simplification above rigor and error handling (but no unsafe Rust)
  • Make it possible to industrialize and configure workflows (eg. data preprocessing, model building, training, evaluation...)
  • Trying not to be 1000x harder than Python and 10x slower than C++ (otherwise what's the point?)

Side/future goals:

  • Implement rare but interesting algorithms (Direct layers, Forward Layers...)
  • WebAssembly and WebGPU support
  • Rust-native GPU backend via wgpu (I can dream, right?)
  • Python bindings via PyO3
  • Graphic tool for model building


  • Data visualization
  • Compliance with other frameworks/standards
  • Perfect error handling (don't be ashamed of unwrap and expect)


Switch backends via Cargo features:

  • arrayfire (CPU/GPU)
    • ✅ Vision available
    • ✅ GPU support
    • 🫤 Slower CPU support
    • 🫤 Hard to install (see Installing Arrayfire)
    • 🫤 C++ library, segfaults...
  • ndarray
    • ✅ Fastest CPU backend
    • ✅ Pure Rust
    • 🫤 Vision not (yet) available
    • 🫤 CPU only
  • nalgebra
    • ✅ Pure Rust
    • 🫤 Vision not available (and not planned)
    • 🫤 CPU only


You can enable precision up to f64 with the f64 feature.

Precision below f32 is not supported (yet).

Installing Arrayfire

You need to first install Arrayfire in order to use the arrayfire feature for fast compute on the CPU or the GPU using Arrayfire's C++/CUDA/OpenCL backends (it will first try OpenCL if installed, then CUDA, then C++). Make sure all the steps of the installation work 100% with no weird warning, as they may fail in quite subtle ways.

Once you installed Arrayfire, you:

  1. Set the AF_PATH to your Arrayfire installation directory (for example: /opt/Arrayfire).
  2. Add the path to lib files to the environement variables:
    • Windows: Add %AF_PATH%\lib to PATH
  3. Run sudo ldconfig if on Linux
  4. Run cargo clean
  5. Disable default features and activate the arrayfire feature
jiro_nn = { 
    version = "*", 
    default_features = false, 
    features = ["arrayfire"] 

If you want to use the CUDA capabilities of Arrayfire on Linux (was tested on Windows 11 WSL2 with Ubuntu and a RTX 3060), check out this guide.


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