# LIBMF Rust
[LIBMF](https://github.com/cjlin1/libmf) - large-scale sparse matrix factorization - for Rust
Check out [Disco](https://github.com/ankane/disco-rust) for higher-level collaborative filtering
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## Installation
Add this line to your application’s `Cargo.toml` under `[dependencies]`:
```toml
libmf = "0.2"
```
## Getting Started
Prep your data in the format `row_index, column_index, value`
```rust
let mut data = libmf::Matrix::new();
data.push(0, 0, 5.0);
data.push(0, 2, 3.5);
data.push(1, 1, 4.0);
```
Fit a model
```rust
let model = libmf::Model::params().fit(&data).unwrap();
```
Make predictions
```rust
model.predict(row_index, column_index);
```
Get the latent factors (these approximate the training matrix)
```rust
model.p(row_index);
model.q(column_index);
// or
model.p_iter();
model.q_iter();
```
Get the bias (average of all elements in the training matrix)
```rust
model.bias();
```
Save the model to a file
```rust
model.save("model.txt").unwrap();
```
Load the model from a file
```rust
let model = libmf::Model::load("model.txt").unwrap();
```
Pass a validation set
```rust
let model = libmf::Model::params().fit_eval(&train_set, &eval_set).unwrap();
```
## Cross-Validation
Perform cross-validation
```rust
let avg_error = libmf::Model::params().cv(&data, 5).unwrap();
```
## Parameters
Set parameters - default values below
```rust
libmf::Model::params()
.loss(libmf::Loss::RealL2) // loss function
.factors(8) // number of latent factors
.threads(12) // number of threads used
.bins(25) // number of bins
.iterations(20) // number of iterations
.lambda_p1(0.0) // coefficient of L1-norm regularization on P
.lambda_p2(0.1) // coefficient of L2-norm regularization on P
.lambda_q1(0.0) // coefficient of L1-norm regularization on Q
.lambda_q2(0.1) // coefficient of L2-norm regularization on Q
.learning_rate(0.1) // learning rate
.alpha(1.0) // importance of negative entries
.c(0.0001) // desired value of negative entries
.nmf(false) // perform non-negative MF (NMF)
.quiet(false); // no outputs to stdout
```
### Loss Functions
For real-valued matrix factorization
- `Loss::RealL2` - squared error (L2-norm)
- `Loss::RealL1` - absolute error (L1-norm)
- `Loss::RealKL` - generalized KL-divergence
For binary matrix factorization
- `Loss::BinaryLog` - logarithmic error
- `Loss::BinaryL2` - squared hinge loss
- `Loss::BinaryL1` - hinge loss
For one-class matrix factorization
- `Loss::OneClassRow` - row-oriented pair-wise logarithmic loss
- `Loss::OneClassCol` - column-oriented pair-wise logarithmic loss
- `Loss::OneClassL2` - squared error (L2-norm)
## Metrics
Calculate RMSE (for real-valued MF)
```rust
model.rmse(&data);
```
Calculate MAE (for real-valued MF)
```rust
model.mae(&data);
```
Calculate generalized KL-divergence (for non-negative real-valued MF)
```rust
model.gkl(&data);
```
Calculate logarithmic loss (for binary MF)
```rust
model.logloss(&data);
```
Calculate accuracy (for binary MF)
```rust
model.accuracy(&data);
```
Calculate MPR (for one-class MF)
```rust
model.mpr(&data, transpose);
```
Calculate AUC (for one-class MF)
```rust
model.auc(&data, transpose);
```
## Example
Download the [MovieLens 100K dataset](https://grouplens.org/datasets/movielens/100k/).
Add these lines to your application’s `Cargo.toml` under `[dependencies]`:
```toml
csv = "1"
serde = { version = "1", features = ["derive"] }
```
And use:
```rust
use csv::ReaderBuilder;
use serde::Deserialize;
use std::fs::File;
#[derive(Debug, Deserialize)]
struct Row {
user_id: i32,
item_id: i32,
rating: f32,
time: i32,
}
fn main() {
let mut train_set = libmf::Matrix::new();
let mut valid_set = libmf::Matrix::new();
let file = File::open("u.data").unwrap();
let mut rdr = ReaderBuilder::new()
.has_headers(false)
.delimiter(b'\t')
.from_reader(file);
for (i, record) in rdr.records().enumerate() {
let row: Row = record.unwrap().deserialize(None).unwrap();
let matrix = if i < 80000 { &mut train_set } else { &mut valid_set };
matrix.push(row.user_id, row.item_id, row.rating);
}
let model = libmf::Model::params().fit_eval(&train_set, &valid_set).unwrap();
println!("RMSE: {:?}", model.rmse(&valid_set));
}
```
## Reference
Specify the initial capacity for a matrix
```rust
let mut data = libmf::Matrix::with_capacity(3);
```
## Resources
- [LIBMF: A Library for Parallel Matrix Factorization in Shared-memory Systems](https://www.csie.ntu.edu.tw/~cjlin/papers/libmf/libmf_open_source.pdf)
## Upgrading
### 0.2.0
Use
```rust
let model = libmf::Model::params().factors(20).fit(&data).unwrap();
```
instead of
```rust
let mut model = libmf::Model::new();
model.factors = 20;
model.fit(&data);
```
## History
View the [changelog](https://github.com/ankane/libmf-rust/blob/master/CHANGELOG.md)
## Contributing
Everyone is encouraged to help improve this project. Here are a few ways you can help:
- [Report bugs](https://github.com/ankane/libmf-rust/issues)
- Fix bugs and [submit pull requests](https://github.com/ankane/libmf-rust/pulls)
- Write, clarify, or fix documentation
- Suggest or add new features
To get started with development:
```sh
git clone --recursive https://github.com/ankane/libmf-rust.git
cd libmf-rust
cargo test
```