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use learning::LearningResult;
use learning::error::Error;
use linalg::{Matrix, BaseMatrix, BaseMatrixMut};
use super::Transformer;
use rand::{Rng, thread_rng, ThreadRng};
#[derive(Debug)]
pub struct Shuffler<R: Rng> {
rng: R,
}
impl<R: Rng> Shuffler<R> {
pub fn new(rng: R) -> Self {
Shuffler { rng: rng }
}
}
impl Default for Shuffler<ThreadRng> {
fn default() -> Self {
Shuffler { rng: thread_rng() }
}
}
impl<R: Rng, T> Transformer<Matrix<T>> for Shuffler<R> {
#[allow(unused_variables)]
fn fit(&mut self, inputs: &Matrix<T>) -> Result<(), Error> {
Ok(())
}
fn transform(&mut self, mut inputs: Matrix<T>) -> LearningResult<Matrix<T>> {
let n = inputs.rows();
for i in 0..n {
let j = self.rng.gen_range(0, n - i);
inputs.swap_rows(i, i + j);
}
Ok(inputs)
}
}
#[cfg(test)]
mod tests {
use linalg::Matrix;
use super::super::Transformer;
use super::Shuffler;
use rand::{StdRng, SeedableRng};
#[test]
fn seeded_shuffle() {
let rng = StdRng::from_seed(&[1, 2, 3]);
let mut shuffler = Shuffler::new(rng);
let mat = Matrix::new(4, 2, vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0]);
let shuffled = shuffler.transform(mat).unwrap();
assert_eq!(shuffled.into_vec(),
vec![3.0, 4.0, 1.0, 2.0, 7.0, 8.0, 5.0, 6.0]);
}
#[test]
fn shuffle_single_row() {
let mut shuffler = Shuffler::default();
let mat = Matrix::new(1, 8, vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0]);
let shuffled = shuffler.transform(mat).unwrap();
assert_eq!(shuffled.into_vec(),
vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0]);
}
#[test]
fn shuffle_fit() {
let rng = StdRng::from_seed(&[1, 2, 3]);
let mut shuffler = Shuffler::new(rng);
let mat = Matrix::new(4, 2, vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0]);
let res = shuffler.fit(&mat).unwrap();
assert_eq!(res, ());
}
}