polars_arrow/legacy/kernels/rolling/no_nulls/
mean.rs

1use polars_error::polars_ensure;
2
3use super::*;
4
5pub struct MeanWindow<'a, T> {
6    sum: SumWindow<'a, T>,
7}
8
9impl<
10        'a,
11        T: NativeType + IsFloat + std::iter::Sum + AddAssign + SubAssign + Div<Output = T> + NumCast,
12    > RollingAggWindowNoNulls<'a, T> for MeanWindow<'a, T>
13{
14    fn new(slice: &'a [T], start: usize, end: usize, params: Option<RollingFnParams>) -> Self {
15        Self {
16            sum: SumWindow::new(slice, start, end, params),
17        }
18    }
19
20    unsafe fn update(&mut self, start: usize, end: usize) -> Option<T> {
21        let sum = self.sum.update(start, end).unwrap_unchecked();
22        Some(sum / NumCast::from(end - start).unwrap())
23    }
24}
25
26pub fn rolling_mean<T>(
27    values: &[T],
28    window_size: usize,
29    min_periods: usize,
30    center: bool,
31    weights: Option<&[f64]>,
32    _params: Option<RollingFnParams>,
33) -> PolarsResult<ArrayRef>
34where
35    T: NativeType + Float + std::iter::Sum<T> + SubAssign + AddAssign + IsFloat,
36{
37    let offset_fn = match center {
38        true => det_offsets_center,
39        false => det_offsets,
40    };
41    match weights {
42        None => rolling_apply_agg_window::<MeanWindow<_>, _, _>(
43            values,
44            window_size,
45            min_periods,
46            offset_fn,
47            None,
48        ),
49        Some(weights) => {
50            // A weighted mean is a weighted sum with normalized weights
51            let mut wts = no_nulls::coerce_weights(weights);
52            let wsum = wts.iter().fold(T::zero(), |acc, x| acc + *x);
53            polars_ensure!(
54                wsum != T::zero(),
55                ComputeError: "Weighted mean is undefined if weights sum to 0"
56            );
57            wts.iter_mut().for_each(|w| *w = *w / wsum);
58            no_nulls::rolling_apply_weights(
59                values,
60                window_size,
61                min_periods,
62                offset_fn,
63                no_nulls::compute_sum_weights,
64                &wts,
65            )
66        },
67    }
68}
polars_arrow/legacy/kernels/rolling/no_nulls/mean.rs

polars_arrow/legacy/kernels/rolling/no_nulls/
mean.rs
