use crate::evaluator::*;
macro_const! {
const DOC: &'static str = r#"
Reduced $\chi^2$ of magnitude measurements
$$
\mathrm{reduced~}\chi^2 \equiv \frac1{N-1} \sum_i\left(\frac{m_i - \bar{m}}{\delta\_i}\right)^2,
$$
where $N$ is the number of observations,
and $\bar{m}$ is the weighted mean magnitude.
- Depends on: **magnitude**, **magnitude error**
- Minimum number of observations: **2**
- Number of features: **1**
This is a good measure of variability which takes into account observations uncertainties.
[Wikipedia](https://en.wikipedia.org/wiki/Reduced_chi-squared_statistic)
"#;
}
#[doc = DOC!()]
#[derive(Clone, Default, Debug, Serialize, Deserialize, JsonSchema)]
pub struct ReducedChi2 {}
lazy_info!(
REDUCED_CHI2_INFO,
ReducedChi2,
size: 1,
min_ts_length: 2,
t_required: false,
m_required: true,
w_required: true,
sorting_required: false,
);
impl ReducedChi2 {
pub fn new() -> Self {
Self {}
}
pub fn doc() -> &'static str {
DOC
}
}
impl FeatureNamesDescriptionsTrait for ReducedChi2 {
fn get_names(&self) -> Vec<&str> {
vec!["chi2"]
}
fn get_descriptions(&self) -> Vec<&str> {
vec!["reduced chi2 as a goodness of constant fit with respect to observation errors"]
}
}
impl<T> FeatureEvaluator<T> for ReducedChi2
where
T: Float,
{
fn eval(&self, ts: &mut TimeSeries<T>) -> Result<Vec<T>, EvaluatorError> {
self.check_ts_length(ts)?;
Ok(vec![ts.get_m_reduced_chi2()])
}
}
#[cfg(test)]
#[allow(clippy::unreadable_literal)]
#[allow(clippy::excessive_precision)]
mod tests {
use super::*;
use crate::tests::*;
check_feature!(ReducedChi2);
feature_test!(
reduced_chi2,
[ReducedChi2::default()],
[2.192592592592593],
[0.0_f64; 10], [1.0, 2.0, 1.0, 0.0, -1.0, 0.0, 1.0, 2.0, -2.0, 0.0],
[1.0, 2.0, 1.0, 2.0, 1.0, 2.0, 1.0, 2.0, 1.0, 2.0],
);
}