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slice.rs
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slice.rs
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use std::sync::Arc;
use polars_core::frame::group_by::{GroupsProxy, IdxItem};
use polars_core::prelude::*;
use polars_core::utils::{slice_offsets, CustomIterTools};
use polars_core::POOL;
use rayon::prelude::*;
use AnyValue::Null;
use crate::physical_plan::state::ExecutionState;
use crate::prelude::*;
pub struct SliceExpr {
pub(crate) input: Arc<dyn PhysicalExpr>,
pub(crate) offset: Arc<dyn PhysicalExpr>,
pub(crate) length: Arc<dyn PhysicalExpr>,
pub(crate) expr: Expr,
}
fn extract_offset(offset: &Series, expr: &Expr) -> PolarsResult<i64> {
polars_ensure!(
offset.len() <= 1, expr = expr, ComputeError:
"invalid argument to slice; expected an offset literal, got series of length {}",
offset.len()
);
offset.get(0).unwrap().extract().ok_or_else(
|| polars_err!(expr = expr, ComputeError: "unable to extract offset from {:?}", offset),
)
}
fn extract_length(length: &Series, expr: &Expr) -> PolarsResult<usize> {
polars_ensure!(
length.len() <= 1, expr = expr, ComputeError:
"invalid argument to slice; expected a length literal, got series of length {}",
length.len()
);
match length.get(0).unwrap() {
Null => Ok(usize::MAX),
v => v.extract().ok_or_else(
|| polars_err!(expr = expr, ComputeError: "unable to extract length from {:?}", length),
),
}
}
fn extract_args(offset: &Series, length: &Series, expr: &Expr) -> PolarsResult<(i64, usize)> {
Ok((extract_offset(offset, expr)?, extract_length(length, expr)?))
}
fn check_argument(arg: &Series, groups: &GroupsProxy, name: &str, expr: &Expr) -> PolarsResult<()> {
polars_ensure!(
!matches!(arg.dtype(), DataType::List(_)), expr = expr, ComputeError:
"invalid slice argument: cannot use an array as {} argument", name,
);
polars_ensure!(
arg.len() == groups.len(), expr = expr, ComputeError:
"invalid slice argument: the evaluated length expression was \
of different {} than the number of groups", name
);
polars_ensure!(
arg.null_count() == 0, expr = expr, ComputeError:
"invalid slice argument: the {} expression has nulls", name
);
Ok(())
}
fn slice_groups_idx(offset: i64, length: usize, first: IdxSize, idx: &[IdxSize]) -> IdxItem {
let (offset, len) = slice_offsets(offset, length, idx.len());
(first + offset as IdxSize, idx[offset..offset + len].into())
}
fn slice_groups_slice(offset: i64, length: usize, first: IdxSize, len: IdxSize) -> [IdxSize; 2] {
let (offset, len) = slice_offsets(offset, length, len as usize);
[first + offset as IdxSize, len as IdxSize]
}
impl PhysicalExpr for SliceExpr {
fn as_expression(&self) -> Option<&Expr> {
Some(&self.expr)
}
fn evaluate(&self, df: &DataFrame, state: &ExecutionState) -> PolarsResult<Series> {
let results = POOL.install(|| {
[&self.offset, &self.length, &self.input]
.par_iter()
.map(|e| e.evaluate(df, state))
.collect::<PolarsResult<Vec<_>>>()
})?;
let offset = &results[0];
let length = &results[1];
let series = &results[2];
let (offset, length) = extract_args(offset, length, &self.expr)?;
Ok(series.slice(offset, length))
}
fn evaluate_on_groups<'a>(
&self,
df: &DataFrame,
groups: &'a GroupsProxy,
state: &ExecutionState,
) -> PolarsResult<AggregationContext<'a>> {
let mut results = POOL.install(|| {
[&self.offset, &self.length, &self.input]
.par_iter()
.map(|e| e.evaluate_on_groups(df, groups, state))
.collect::<PolarsResult<Vec<_>>>()
})?;
let mut ac = results.pop().unwrap();
let mut ac_length = results.pop().unwrap();
let mut ac_offset = results.pop().unwrap();
let groups = ac.groups();
use AggState::*;
let groups = match (&ac_offset.state, &ac_length.state) {
(Literal(offset), Literal(length)) => {
let (offset, length) = extract_args(offset, length, &self.expr)?;
match groups.as_ref() {
GroupsProxy::Idx(groups) => {
let groups = groups
.iter()
.map(|(first, idx)| slice_groups_idx(offset, length, first, idx))
.collect();
GroupsProxy::Idx(groups)
},
GroupsProxy::Slice { groups, .. } => {
let groups = groups
.iter()
.map(|&[first, len]| slice_groups_slice(offset, length, first, len))
.collect_trusted();
GroupsProxy::Slice {
groups,
rolling: false,
}
},
}
},
(Literal(offset), _) => {
let offset = extract_offset(offset, &self.expr)?;
let length = ac_length.aggregated();
check_argument(&length, groups, "length", &self.expr)?;
let length = length.cast(&IDX_DTYPE)?;
let length = length.idx().unwrap();
match groups.as_ref() {
GroupsProxy::Idx(groups) => {
let groups = groups
.iter()
.zip(length.into_no_null_iter())
.map(|((first, idx), length)| {
slice_groups_idx(offset, length as usize, first, idx)
})
.collect();
GroupsProxy::Idx(groups)
},
GroupsProxy::Slice { groups, .. } => {
let groups = groups
.iter()
.zip(length.into_no_null_iter())
.map(|(&[first, len], length)| {
slice_groups_slice(offset, length as usize, first, len)
})
.collect_trusted();
GroupsProxy::Slice {
groups,
rolling: false,
}
},
}
},
(_, Literal(length)) => {
let length = extract_length(length, &self.expr)?;
let offset = ac_offset.aggregated();
check_argument(&offset, groups, "offset", &self.expr)?;
let offset = offset.cast(&DataType::Int64)?;
let offset = offset.i64().unwrap();
match groups.as_ref() {
GroupsProxy::Idx(groups) => {
let groups = groups
.iter()
.zip(offset.into_no_null_iter())
.map(|((first, idx), offset)| {
slice_groups_idx(offset, length, first, idx)
})
.collect();
GroupsProxy::Idx(groups)
},
GroupsProxy::Slice { groups, .. } => {
let groups = groups
.iter()
.zip(offset.into_no_null_iter())
.map(|(&[first, len], offset)| {
slice_groups_slice(offset, length, first, len)
})
.collect_trusted();
GroupsProxy::Slice {
groups,
rolling: false,
}
},
}
},
_ => {
let length = ac_length.aggregated();
let offset = ac_offset.aggregated();
check_argument(&length, groups, "length", &self.expr)?;
check_argument(&offset, groups, "offset", &self.expr)?;
let offset = offset.cast(&DataType::Int64)?;
let offset = offset.i64().unwrap();
let length = length.cast(&IDX_DTYPE)?;
let length = length.idx().unwrap();
match groups.as_ref() {
GroupsProxy::Idx(groups) => {
let groups = groups
.iter()
.zip(offset.into_no_null_iter())
.zip(length.into_no_null_iter())
.map(|(((first, idx), offset), length)| {
slice_groups_idx(offset, length as usize, first, idx)
})
.collect();
GroupsProxy::Idx(groups)
},
GroupsProxy::Slice { groups, .. } => {
let groups = groups
.iter()
.zip(offset.into_no_null_iter())
.zip(length.into_no_null_iter())
.map(|((&[first, len], offset), length)| {
slice_groups_slice(offset, length as usize, first, len)
})
.collect_trusted();
GroupsProxy::Slice {
groups,
rolling: false,
}
},
}
},
};
ac.with_groups(groups).set_original_len(false);
Ok(ac)
}
fn to_field(&self, input_schema: &Schema) -> PolarsResult<Field> {
self.input.to_field(input_schema)
}
}