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#[derive(Clone)]
pub struct RollingOptionsFixedWindow {
pub window_size: usize,
pub min_periods: usize,
pub weights: Option<Vec<f64>>,
pub center: bool,
}
impl Default for RollingOptionsFixedWindow {
fn default() -> Self {
RollingOptionsFixedWindow {
window_size: 3,
min_periods: 1,
weights: None,
center: false,
}
}
}
#[cfg(feature = "rolling_window")]
mod inner_mod {
use std::ops::SubAssign;
use arrow::array::{Array, PrimitiveArray};
use arrow::bitmap::MutableBitmap;
use num::{Float, Zero};
use polars_arrow::bit_util::unset_bit_raw;
use polars_arrow::data_types::IsFloat;
use polars_arrow::trusted_len::PushUnchecked;
use crate::prelude::*;
fn check_input(window_size: usize, min_periods: usize) -> PolarsResult<()> {
if min_periods > window_size {
Err(PolarsError::ComputeError(
"`windows_size` should be >= `min_periods`".into(),
))
} else {
Ok(())
}
}
fn window_edges(idx: usize, len: usize, window_size: usize, center: bool) -> (usize, usize) {
let (start, end) = if center {
let right_window = (window_size + 1) / 2;
(
idx.saturating_sub(window_size - right_window),
std::cmp::min(len, idx + right_window),
)
} else {
(idx.saturating_sub(window_size - 1), idx + 1)
};
(start, end - start)
}
impl<T> ChunkRollApply for ChunkedArray<T>
where
T: PolarsNumericType,
Self: IntoSeries,
{
fn rolling_apply(
&self,
f: &dyn Fn(&Series) -> Series,
options: RollingOptionsFixedWindow,
) -> PolarsResult<Series> {
check_input(options.window_size, options.min_periods)?;
let ca = self.rechunk();
if options.weights.is_some()
&& !matches!(self.dtype(), DataType::Float64 | DataType::Float32)
{
let s = self.cast(&DataType::Float64)?;
return s.rolling_apply(f, options);
}
if options.window_size >= self.len() {
return Ok(Self::full_null(self.name(), self.len()).into_series());
}
let len = self.len();
let arr = ca.downcast_iter().next().unwrap();
let mut series_container =
ChunkedArray::<T>::from_slice("", &[T::Native::zero()]).into_series();
let array_ptr = series_container.array_ref(0);
let ptr = array_ptr.as_ref() as *const dyn Array as *mut dyn Array
as *mut PrimitiveArray<T::Native>;
let mut builder = PrimitiveChunkedBuilder::<T>::new(self.name(), self.len());
if let Some(weights) = options.weights {
let weights_series = Float64Chunked::new("weights", &weights).into_series();
let weights_series = weights_series.cast(self.dtype()).unwrap();
for idx in 0..len {
let (start, size) = window_edges(idx, len, options.window_size, options.center);
if size < options.min_periods {
builder.append_null();
} else {
let arr_window = unsafe { arr.slice_unchecked(start, size) };
unsafe {
*ptr = arr_window;
}
series_container._get_inner_mut().compute_len();
let s = if size == options.window_size {
f(&series_container.multiply(&weights_series).unwrap())
} else {
let weights_cutoff: Series = match self.dtype() {
DataType::Float64 => weights_series
.f64()
.unwrap()
.into_iter()
.take(series_container.len())
.collect(),
_ => weights_series .f32()
.unwrap()
.into_iter()
.take(series_container.len())
.collect(),
};
f(&series_container.multiply(&weights_cutoff).unwrap())
};
let out = self.unpack_series_matching_type(&s)?;
builder.append_option(out.get(0));
}
}
Ok(builder.finish().into_series())
} else {
for idx in 0..len {
let (start, size) = window_edges(idx, len, options.window_size, options.center);
if size < options.min_periods {
builder.append_null();
} else {
let arr_window = unsafe { arr.slice_unchecked(start, size) };
unsafe {
*ptr = arr_window;
}
series_container._get_inner_mut().compute_len();
let s = f(&series_container);
let out = self.unpack_series_matching_type(&s)?;
builder.append_option(out.get(0));
}
}
Ok(builder.finish().into_series())
}
}
}
impl<T> ChunkedArray<T>
where
ChunkedArray<T>: IntoSeries,
T: PolarsFloatType,
T::Native: Float + IsFloat + SubAssign + num::pow::Pow<T::Native, Output = T::Native>,
{
pub fn rolling_apply_float<F>(&self, window_size: usize, mut f: F) -> PolarsResult<Self>
where
F: FnMut(&mut ChunkedArray<T>) -> Option<T::Native>,
{
if window_size >= self.len() {
return Ok(Self::full_null(self.name(), self.len()));
}
let ca = self.rechunk();
let arr = ca.downcast_iter().next().unwrap();
let mut heap_container = ChunkedArray::<T>::from_slice("", &[T::Native::zero()]);
let array_ptr = &heap_container.chunks()[0];
let ptr = array_ptr.as_ref() as *const dyn Array as *mut dyn Array
as *mut PrimitiveArray<T::Native>;
let mut validity = MutableBitmap::with_capacity(ca.len());
validity.extend_constant(window_size - 1, false);
validity.extend_constant(ca.len() - (window_size - 1), true);
let validity_ptr = validity.as_slice().as_ptr() as *mut u8;
let mut values = Vec::with_capacity(ca.len());
values.extend(std::iter::repeat(T::Native::default()).take(window_size - 1));
for offset in 0..self.len() + 1 - window_size {
debug_assert!(offset + window_size <= arr.len());
let arr_window = unsafe { arr.slice_unchecked(offset, window_size) };
heap_container.length = arr_window.len() as IdxSize;
unsafe {
*ptr = arr_window;
}
let out = f(&mut heap_container);
match out {
Some(v) => unsafe { values.push_unchecked(v) },
None => unsafe { unset_bit_raw(validity_ptr, offset + window_size - 1) },
}
}
let arr = PrimitiveArray::from_data(
T::get_dtype().to_arrow(),
values.into(),
Some(validity.into()),
);
Ok(Self::from_chunks(self.name(), vec![Box::new(arr)]))
}
}
}
#[cfg(feature = "rolling_window")]
pub use inner_mod::*;