1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

use crate::evaluator::*;

use conv::ConvUtil;

/// Fraction of observations beyond $n\\,\sigma\_m$ from the mean magnitude $\langle m \rangle$
///
/// $$
/// \mathrm{beyond}~n\\,\sigma\_m \equiv \frac{\sum\_i I\_{|m - \langle m \rangle| > n\\,\sigma\_m}(m_i)}{N},
/// $$
/// where $I$ is the [indicator function](https://en.wikipedia.org/wiki/Indicator_function),
/// $N$ is the number of observations,
/// $\langle m \rangle$ is the mean magnitude
/// and $\sigma_m = \sqrt{\sum_i (m_i - \langle m \rangle)^2 / (N-1)}$ is the magnitude standard deviation.
///
/// - Depends on: **magnitude**
/// - Minimum number of observations: **2**
/// - Number of features: **1**
///
/// D’Isanto et al. 2016 [DOI:10.1093/mnras/stw157](https://doi.org/10.1093/mnras/stw157)
/// ```
/// use light_curve_feature::*;
/// use light_curve_common::all_close;
/// use std::f64::consts::SQRT_2;
///
/// let fe = feat_extr!(BeyondNStd::default(), BeyondNStd::new(2.0));
/// let time = [0.0; 21];  // Doesn't depend on time
/// let mut magn = vec![0.0; 17];
/// magn.extend_from_slice(&[SQRT_2, -SQRT_2, 2.0 * SQRT_2, -2.0 * SQRT_2]);
/// let mut ts = TimeSeries::new(&time[..], &magn[..], None);
/// assert_eq!(0.0, ts.m.get_mean());
/// assert!((1.0 - ts.m.get_std()).abs() < 1e-15);
/// assert_eq!(vec![4.0 / 21.0, 2.0 / 21.0], fe.eval(&mut ts).unwrap());
/// ```
#[derive(Clone, Debug)]
pub struct BeyondNStd<T> {
    nstd: T,
    name: String,
    description: String,
}

impl<T> BeyondNStd<T>
where
    T: Float,
{
    pub fn new(nstd: T) -> Self {
        assert!(nstd > T::zero(), "nstd should be positive");
        Self {
            nstd,
            name: format!("beyond_{:.0}_std", nstd),
            description: format!(
                "fraction of observations which magnitudes are beyond {:.3e} standard deviations \
                from the mean magnitude",
                nstd
            ),
        }
    }

    pub fn set_name(&mut self, name: String) {
        self.name = name;
    }

    #[inline]
    pub fn default_nstd() -> T {
        T::one()
    }
}

lazy_info!(
    BEYOND_N_STD_INFO,
    size: 1,
    min_ts_length: 2,
    t_required: false,
    m_required: true,
    w_required: false,
    sorting_required: false,
);

impl<T> Default for BeyondNStd<T>
where
    T: Float,
{
    fn default() -> Self {
        Self::new(Self::default_nstd())
    }
}

impl<T> FeatureEvaluator<T> for BeyondNStd<T>
where
    T: Float,
{
    fn eval(&self, ts: &mut TimeSeries<T>) -> Result<Vec<T>, EvaluatorError> {
        self.check_ts_length(ts)?;
        let m_mean = ts.m.get_mean();
        let threshold = ts.m.get_std() * self.nstd;
        Ok(vec![
            ts.m.sample
                .iter()
                .filter(|&&y| T::abs(y - m_mean) > threshold)
                .count()
                .value_as::<T>()
                .unwrap()
                / ts.lenf(),
        ])
    }

    fn get_info(&self) -> &EvaluatorInfo {
        &BEYOND_N_STD_INFO
    }

    fn get_names(&self) -> Vec<&str> {
        vec![self.name.as_str()]
    }

    fn get_descriptions(&self) -> Vec<&str> {
        vec![self.description.as_str()]
    }
}

#[cfg(test)]
#[allow(clippy::unreadable_literal)]
#[allow(clippy::excessive_precision)]
mod tests {
    use super::*;
    use crate::tests::*;

    eval_info_test!(beyond_n_std_info, BeyondNStd::default());

    feature_test!(
        beyond_n_std,
        [
            Box::new(BeyondNStd::default()),
            Box::new(BeyondNStd::new(1.0)), // should be the same as the previous one
            Box::new(BeyondNStd::new(2.0)),
        ],
        [0.2, 0.2, 0.0],
        [1.0_f32, 2.0, 3.0, 4.0, 100.0],
    );
}