polars_core/frame/group_by/
position.rs

1use std::mem::ManuallyDrop;
2use std::ops::{Deref, DerefMut};
3
4use arrow::offset::OffsetsBuffer;
5use polars_utils::idx_vec::IdxVec;
6use rayon::iter::plumbing::UnindexedConsumer;
7use rayon::prelude::*;
8
9use crate::prelude::*;
10use crate::utils::{flatten, slice_slice, NoNull};
11use crate::POOL;
12
13/// Indexes of the groups, the first index is stored separately.
14/// this make sorting fast.
15#[derive(Debug, Clone, PartialEq, Eq, Default)]
16pub struct GroupsIdx {
17    pub(crate) sorted: bool,
18    first: Vec<IdxSize>,
19    all: Vec<IdxVec>,
20}
21
22pub type IdxItem = (IdxSize, IdxVec);
23pub type BorrowIdxItem<'a> = (IdxSize, &'a IdxVec);
24
25impl Drop for GroupsIdx {
26    fn drop(&mut self) {
27        let v = std::mem::take(&mut self.all);
28        // ~65k took approximately 1ms on local machine, so from that point we drop on other thread
29        // to stop query from being blocked
30        #[cfg(not(target_family = "wasm"))]
31        if v.len() > 1 << 16 {
32            std::thread::spawn(move || drop(v));
33        } else {
34            drop(v);
35        }
36
37        #[cfg(target_family = "wasm")]
38        drop(v);
39    }
40}
41
42impl From<Vec<IdxItem>> for GroupsIdx {
43    fn from(v: Vec<IdxItem>) -> Self {
44        v.into_iter().collect()
45    }
46}
47
48impl From<Vec<Vec<IdxItem>>> for GroupsIdx {
49    fn from(v: Vec<Vec<IdxItem>>) -> Self {
50        // single threaded flatten: 10% faster than `iter().flatten().collect()
51        // this is the multi-threaded impl of that
52        let (cap, offsets) = flatten::cap_and_offsets(&v);
53        let mut first = Vec::with_capacity(cap);
54        let first_ptr = first.as_ptr() as usize;
55        let mut all = Vec::with_capacity(cap);
56        let all_ptr = all.as_ptr() as usize;
57
58        POOL.install(|| {
59            v.into_par_iter()
60                .zip(offsets)
61                .for_each(|(mut inner, offset)| {
62                    unsafe {
63                        let first = (first_ptr as *const IdxSize as *mut IdxSize).add(offset);
64                        let all = (all_ptr as *const IdxVec as *mut IdxVec).add(offset);
65
66                        let inner_ptr = inner.as_mut_ptr();
67                        for i in 0..inner.len() {
68                            let (first_val, vals) = std::ptr::read(inner_ptr.add(i));
69                            std::ptr::write(first.add(i), first_val);
70                            std::ptr::write(all.add(i), vals);
71                        }
72                        // set len to 0 so that the contents will not get dropped
73                        // they are moved to `first` and `all`
74                        inner.set_len(0);
75                    }
76                });
77        });
78        unsafe {
79            all.set_len(cap);
80            first.set_len(cap);
81        }
82        GroupsIdx {
83            sorted: false,
84            first,
85            all,
86        }
87    }
88}
89
90impl GroupsIdx {
91    pub fn new(first: Vec<IdxSize>, all: Vec<IdxVec>, sorted: bool) -> Self {
92        Self { sorted, first, all }
93    }
94
95    pub fn sort(&mut self) {
96        if self.sorted {
97            return;
98        }
99        let mut idx = 0;
100        let first = std::mem::take(&mut self.first);
101        // store index and values so that we can sort those
102        let mut idx_vals = first
103            .into_iter()
104            .map(|v| {
105                let out = [idx, v];
106                idx += 1;
107                out
108            })
109            .collect_trusted::<Vec<_>>();
110        idx_vals.sort_unstable_by_key(|v| v[1]);
111
112        let take_first = || idx_vals.iter().map(|v| v[1]).collect_trusted::<Vec<_>>();
113        let take_all = || {
114            idx_vals
115                .iter()
116                .map(|v| unsafe {
117                    let idx = v[0] as usize;
118                    std::mem::take(self.all.get_unchecked_mut(idx))
119                })
120                .collect_trusted::<Vec<_>>()
121        };
122        let (first, all) = POOL.install(|| rayon::join(take_first, take_all));
123        self.first = first;
124        self.all = all;
125        self.sorted = true
126    }
127    pub fn is_sorted_flag(&self) -> bool {
128        self.sorted
129    }
130
131    pub fn iter(
132        &self,
133    ) -> std::iter::Zip<std::iter::Copied<std::slice::Iter<IdxSize>>, std::slice::Iter<IdxVec>>
134    {
135        self.into_iter()
136    }
137
138    pub fn all(&self) -> &[IdxVec] {
139        &self.all
140    }
141
142    pub fn first(&self) -> &[IdxSize] {
143        &self.first
144    }
145
146    pub fn first_mut(&mut self) -> &mut Vec<IdxSize> {
147        &mut self.first
148    }
149
150    pub(crate) fn len(&self) -> usize {
151        self.first.len()
152    }
153
154    pub(crate) unsafe fn get_unchecked(&self, index: usize) -> BorrowIdxItem {
155        let first = *self.first.get_unchecked(index);
156        let all = self.all.get_unchecked(index);
157        (first, all)
158    }
159}
160
161impl FromIterator<IdxItem> for GroupsIdx {
162    fn from_iter<T: IntoIterator<Item = IdxItem>>(iter: T) -> Self {
163        let (first, all) = iter.into_iter().unzip();
164        GroupsIdx {
165            sorted: false,
166            first,
167            all,
168        }
169    }
170}
171
172impl<'a> IntoIterator for &'a GroupsIdx {
173    type Item = BorrowIdxItem<'a>;
174    type IntoIter = std::iter::Zip<
175        std::iter::Copied<std::slice::Iter<'a, IdxSize>>,
176        std::slice::Iter<'a, IdxVec>,
177    >;
178
179    fn into_iter(self) -> Self::IntoIter {
180        self.first.iter().copied().zip(self.all.iter())
181    }
182}
183
184impl IntoIterator for GroupsIdx {
185    type Item = IdxItem;
186    type IntoIter = std::iter::Zip<std::vec::IntoIter<IdxSize>, std::vec::IntoIter<IdxVec>>;
187
188    fn into_iter(mut self) -> Self::IntoIter {
189        let first = std::mem::take(&mut self.first);
190        let all = std::mem::take(&mut self.all);
191        first.into_iter().zip(all)
192    }
193}
194
195impl FromParallelIterator<IdxItem> for GroupsIdx {
196    fn from_par_iter<I>(par_iter: I) -> Self
197    where
198        I: IntoParallelIterator<Item = IdxItem>,
199    {
200        let (first, all) = par_iter.into_par_iter().unzip();
201        GroupsIdx {
202            sorted: false,
203            first,
204            all,
205        }
206    }
207}
208
209impl<'a> IntoParallelIterator for &'a GroupsIdx {
210    type Iter = rayon::iter::Zip<
211        rayon::iter::Copied<rayon::slice::Iter<'a, IdxSize>>,
212        rayon::slice::Iter<'a, IdxVec>,
213    >;
214    type Item = BorrowIdxItem<'a>;
215
216    fn into_par_iter(self) -> Self::Iter {
217        self.first.par_iter().copied().zip(self.all.par_iter())
218    }
219}
220
221impl IntoParallelIterator for GroupsIdx {
222    type Iter = rayon::iter::Zip<rayon::vec::IntoIter<IdxSize>, rayon::vec::IntoIter<IdxVec>>;
223    type Item = IdxItem;
224
225    fn into_par_iter(mut self) -> Self::Iter {
226        let first = std::mem::take(&mut self.first);
227        let all = std::mem::take(&mut self.all);
228        first.into_par_iter().zip(all.into_par_iter())
229    }
230}
231
232/// Every group is indicated by an array where the
233///  - first value is an index to the start of the group
234///  - second value is the length of the group
235///
236/// Only used when group values are stored together
237///
238/// This type should have the invariant that it is always sorted in ascending order.
239pub type GroupsSlice = Vec<[IdxSize; 2]>;
240
241#[derive(Debug, Clone, PartialEq, Eq)]
242pub enum GroupsType {
243    Idx(GroupsIdx),
244    /// Slice is always sorted in ascending order.
245    Slice {
246        // the groups slices
247        groups: GroupsSlice,
248        // indicates if we do a rolling group_by
249        rolling: bool,
250    },
251}
252
253impl Default for GroupsType {
254    fn default() -> Self {
255        GroupsType::Idx(GroupsIdx::default())
256    }
257}
258
259impl GroupsType {
260    pub fn into_idx(self) -> GroupsIdx {
261        match self {
262            GroupsType::Idx(groups) => groups,
263            GroupsType::Slice { groups, .. } => {
264                polars_warn!("Had to reallocate groups, missed an optimization opportunity. Please open an issue.");
265                groups
266                    .iter()
267                    .map(|&[first, len]| (first, (first..first + len).collect::<IdxVec>()))
268                    .collect()
269            },
270        }
271    }
272
273    pub(crate) fn prepare_list_agg(
274        &self,
275        total_len: usize,
276    ) -> (Option<IdxCa>, OffsetsBuffer<i64>, bool) {
277        let mut can_fast_explode = true;
278        match self {
279            GroupsType::Idx(groups) => {
280                let mut list_offset = Vec::with_capacity(self.len() + 1);
281                let mut gather_offsets = Vec::with_capacity(total_len);
282
283                let mut len_so_far = 0i64;
284                list_offset.push(len_so_far);
285
286                for idx in groups {
287                    let idx = idx.1;
288                    gather_offsets.extend_from_slice(idx);
289                    len_so_far += idx.len() as i64;
290                    list_offset.push(len_so_far);
291                    can_fast_explode &= !idx.is_empty();
292                }
293                unsafe {
294                    (
295                        Some(IdxCa::from_vec(PlSmallStr::EMPTY, gather_offsets)),
296                        OffsetsBuffer::new_unchecked(list_offset.into()),
297                        can_fast_explode,
298                    )
299                }
300            },
301            GroupsType::Slice { groups, .. } => {
302                let mut list_offset = Vec::with_capacity(self.len() + 1);
303                let mut gather_offsets = Vec::with_capacity(total_len);
304                let mut len_so_far = 0i64;
305                list_offset.push(len_so_far);
306
307                for g in groups {
308                    let len = g[1];
309                    let offset = g[0];
310                    gather_offsets.extend(offset..offset + len);
311
312                    len_so_far += len as i64;
313                    list_offset.push(len_so_far);
314                    can_fast_explode &= len > 0;
315                }
316
317                unsafe {
318                    (
319                        Some(IdxCa::from_vec(PlSmallStr::EMPTY, gather_offsets)),
320                        OffsetsBuffer::new_unchecked(list_offset.into()),
321                        can_fast_explode,
322                    )
323                }
324            },
325        }
326    }
327
328    pub fn iter(&self) -> GroupsTypeIter {
329        GroupsTypeIter::new(self)
330    }
331
332    pub fn sort(&mut self) {
333        match self {
334            GroupsType::Idx(groups) => {
335                if !groups.is_sorted_flag() {
336                    groups.sort()
337                }
338            },
339            GroupsType::Slice { .. } => {
340                // invariant of the type
341            },
342        }
343    }
344
345    pub(crate) fn is_sorted_flag(&self) -> bool {
346        match self {
347            GroupsType::Idx(groups) => groups.is_sorted_flag(),
348            GroupsType::Slice { .. } => true,
349        }
350    }
351
352    pub fn take_group_firsts(self) -> Vec<IdxSize> {
353        match self {
354            GroupsType::Idx(mut groups) => std::mem::take(&mut groups.first),
355            GroupsType::Slice { groups, .. } => {
356                groups.into_iter().map(|[first, _len]| first).collect()
357            },
358        }
359    }
360
361    /// # Safety
362    /// This will not do any bounds checks. The caller must ensure
363    /// all groups have members.
364    pub unsafe fn take_group_lasts(self) -> Vec<IdxSize> {
365        match self {
366            GroupsType::Idx(groups) => groups
367                .all
368                .iter()
369                .map(|idx| *idx.get_unchecked(idx.len() - 1))
370                .collect(),
371            GroupsType::Slice { groups, .. } => groups
372                .into_iter()
373                .map(|[first, len]| first + len - 1)
374                .collect(),
375        }
376    }
377
378    pub fn par_iter(&self) -> GroupsTypeParIter {
379        GroupsTypeParIter::new(self)
380    }
381
382    /// Get a reference to the `GroupsIdx`.
383    ///
384    /// # Panic
385    ///
386    /// panics if the groups are a slice.
387    pub fn unwrap_idx(&self) -> &GroupsIdx {
388        match self {
389            GroupsType::Idx(groups) => groups,
390            GroupsType::Slice { .. } => panic!("groups are slices not index"),
391        }
392    }
393
394    /// Get a reference to the `GroupsSlice`.
395    ///
396    /// # Panic
397    ///
398    /// panics if the groups are an idx.
399    pub fn unwrap_slice(&self) -> &GroupsSlice {
400        match self {
401            GroupsType::Slice { groups, .. } => groups,
402            GroupsType::Idx(_) => panic!("groups are index not slices"),
403        }
404    }
405
406    pub fn get(&self, index: usize) -> GroupsIndicator {
407        match self {
408            GroupsType::Idx(groups) => {
409                let first = groups.first[index];
410                let all = &groups.all[index];
411                GroupsIndicator::Idx((first, all))
412            },
413            GroupsType::Slice { groups, .. } => GroupsIndicator::Slice(groups[index]),
414        }
415    }
416
417    /// Get a mutable reference to the `GroupsIdx`.
418    ///
419    /// # Panic
420    ///
421    /// panics if the groups are a slice.
422    pub fn idx_mut(&mut self) -> &mut GroupsIdx {
423        match self {
424            GroupsType::Idx(groups) => groups,
425            GroupsType::Slice { .. } => panic!("groups are slices not index"),
426        }
427    }
428
429    pub fn len(&self) -> usize {
430        match self {
431            GroupsType::Idx(groups) => groups.len(),
432            GroupsType::Slice { groups, .. } => groups.len(),
433        }
434    }
435
436    pub fn is_empty(&self) -> bool {
437        self.len() == 0
438    }
439
440    pub fn group_count(&self) -> IdxCa {
441        match self {
442            GroupsType::Idx(groups) => {
443                let ca: NoNull<IdxCa> = groups
444                    .iter()
445                    .map(|(_first, idx)| idx.len() as IdxSize)
446                    .collect_trusted();
447                ca.into_inner()
448            },
449            GroupsType::Slice { groups, .. } => {
450                let ca: NoNull<IdxCa> = groups.iter().map(|[_first, len]| *len).collect_trusted();
451                ca.into_inner()
452            },
453        }
454    }
455    pub fn as_list_chunked(&self) -> ListChunked {
456        match self {
457            GroupsType::Idx(groups) => groups
458                .iter()
459                .map(|(_first, idx)| {
460                    let ca: NoNull<IdxCa> = idx.iter().map(|&v| v as IdxSize).collect();
461                    ca.into_inner().into_series()
462                })
463                .collect_trusted(),
464            GroupsType::Slice { groups, .. } => groups
465                .iter()
466                .map(|&[first, len]| {
467                    let ca: NoNull<IdxCa> = (first..first + len).collect_trusted();
468                    ca.into_inner().into_series()
469                })
470                .collect_trusted(),
471        }
472    }
473
474    pub fn into_sliceable(self) -> GroupPositions {
475        let len = self.len();
476        slice_groups(Arc::new(self), 0, len)
477    }
478}
479
480impl From<GroupsIdx> for GroupsType {
481    fn from(groups: GroupsIdx) -> Self {
482        GroupsType::Idx(groups)
483    }
484}
485
486pub enum GroupsIndicator<'a> {
487    Idx(BorrowIdxItem<'a>),
488    Slice([IdxSize; 2]),
489}
490
491impl GroupsIndicator<'_> {
492    pub fn len(&self) -> usize {
493        match self {
494            GroupsIndicator::Idx(g) => g.1.len(),
495            GroupsIndicator::Slice([_, len]) => *len as usize,
496        }
497    }
498    pub fn first(&self) -> IdxSize {
499        match self {
500            GroupsIndicator::Idx(g) => g.0,
501            GroupsIndicator::Slice([first, _]) => *first,
502        }
503    }
504    pub fn is_empty(&self) -> bool {
505        self.len() == 0
506    }
507}
508
509pub struct GroupsTypeIter<'a> {
510    vals: &'a GroupsType,
511    len: usize,
512    idx: usize,
513}
514
515impl<'a> GroupsTypeIter<'a> {
516    fn new(vals: &'a GroupsType) -> Self {
517        let len = vals.len();
518        let idx = 0;
519        GroupsTypeIter { vals, len, idx }
520    }
521}
522
523impl<'a> Iterator for GroupsTypeIter<'a> {
524    type Item = GroupsIndicator<'a>;
525
526    fn nth(&mut self, n: usize) -> Option<Self::Item> {
527        self.idx = self.idx.saturating_add(n);
528        self.next()
529    }
530
531    fn next(&mut self) -> Option<Self::Item> {
532        if self.idx >= self.len {
533            return None;
534        }
535
536        let out = unsafe {
537            match self.vals {
538                GroupsType::Idx(groups) => {
539                    let item = groups.get_unchecked(self.idx);
540                    Some(GroupsIndicator::Idx(item))
541                },
542                GroupsType::Slice { groups, .. } => {
543                    Some(GroupsIndicator::Slice(*groups.get_unchecked(self.idx)))
544                },
545            }
546        };
547        self.idx += 1;
548        out
549    }
550}
551
552pub struct GroupsTypeParIter<'a> {
553    vals: &'a GroupsType,
554    len: usize,
555}
556
557impl<'a> GroupsTypeParIter<'a> {
558    fn new(vals: &'a GroupsType) -> Self {
559        let len = vals.len();
560        GroupsTypeParIter { vals, len }
561    }
562}
563
564impl<'a> ParallelIterator for GroupsTypeParIter<'a> {
565    type Item = GroupsIndicator<'a>;
566
567    fn drive_unindexed<C>(self, consumer: C) -> C::Result
568    where
569        C: UnindexedConsumer<Self::Item>,
570    {
571        (0..self.len)
572            .into_par_iter()
573            .map(|i| unsafe {
574                match self.vals {
575                    GroupsType::Idx(groups) => GroupsIndicator::Idx(groups.get_unchecked(i)),
576                    GroupsType::Slice { groups, .. } => {
577                        GroupsIndicator::Slice(*groups.get_unchecked(i))
578                    },
579                }
580            })
581            .drive_unindexed(consumer)
582    }
583}
584
585#[derive(Debug)]
586pub struct GroupPositions {
587    sliced: ManuallyDrop<GroupsType>,
588    // Unsliced buffer
589    original: Arc<GroupsType>,
590    offset: i64,
591    len: usize,
592}
593
594impl Clone for GroupPositions {
595    fn clone(&self) -> Self {
596        let sliced = slice_groups_inner(&self.original, self.offset, self.len);
597
598        Self {
599            sliced,
600            original: self.original.clone(),
601            offset: self.offset,
602            len: self.len,
603        }
604    }
605}
606
607impl PartialEq for GroupPositions {
608    fn eq(&self, other: &Self) -> bool {
609        self.offset == other.offset && self.len == other.len && self.sliced == other.sliced
610    }
611}
612
613impl AsRef<GroupsType> for GroupPositions {
614    fn as_ref(&self) -> &GroupsType {
615        self.sliced.deref()
616    }
617}
618
619impl Deref for GroupPositions {
620    type Target = GroupsType;
621
622    fn deref(&self) -> &Self::Target {
623        self.sliced.deref()
624    }
625}
626
627impl Default for GroupPositions {
628    fn default() -> Self {
629        GroupsType::default().into_sliceable()
630    }
631}
632
633impl GroupPositions {
634    pub fn slice(&self, offset: i64, len: usize) -> Self {
635        let offset = self.offset + offset;
636        slice_groups(
637            self.original.clone(),
638            offset,
639            // invariant that len should be in bounds, so truncate if not
640            if len > self.len { self.len } else { len },
641        )
642    }
643
644    pub fn sort(&mut self) {
645        if !self.as_ref().is_sorted_flag() {
646            let original = Arc::make_mut(&mut self.original);
647            original.sort();
648
649            self.sliced = slice_groups_inner(original, self.offset, self.len);
650        }
651    }
652
653    pub fn unroll(mut self) -> GroupPositions {
654        match self.sliced.deref_mut() {
655            GroupsType::Idx(_) => self,
656            GroupsType::Slice { rolling: false, .. } => self,
657            GroupsType::Slice {
658                groups, rolling, ..
659            } => {
660                let mut offset = 0 as IdxSize;
661                for g in groups.iter_mut() {
662                    g[0] = offset;
663                    offset += g[1];
664                }
665                *rolling = false;
666                self
667            },
668        }
669    }
670}
671
672fn slice_groups_inner(g: &GroupsType, offset: i64, len: usize) -> ManuallyDrop<GroupsType> {
673    // SAFETY:
674    // we create new `Vec`s from the sliced groups. But we wrap them in ManuallyDrop
675    // so that we never call drop on them.
676    // These groups lifetimes are bounded to the `g`. This must remain valid
677    // for the scope of the aggregation.
678    match g {
679        GroupsType::Idx(groups) => {
680            let first = unsafe {
681                let first = slice_slice(groups.first(), offset, len);
682                let ptr = first.as_ptr() as *mut _;
683                Vec::from_raw_parts(ptr, first.len(), first.len())
684            };
685
686            let all = unsafe {
687                let all = slice_slice(groups.all(), offset, len);
688                let ptr = all.as_ptr() as *mut _;
689                Vec::from_raw_parts(ptr, all.len(), all.len())
690            };
691            ManuallyDrop::new(GroupsType::Idx(GroupsIdx::new(
692                first,
693                all,
694                groups.is_sorted_flag(),
695            )))
696        },
697        GroupsType::Slice { groups, rolling } => {
698            let groups = unsafe {
699                let groups = slice_slice(groups, offset, len);
700                let ptr = groups.as_ptr() as *mut _;
701                Vec::from_raw_parts(ptr, groups.len(), groups.len())
702            };
703
704            ManuallyDrop::new(GroupsType::Slice {
705                groups,
706                rolling: *rolling,
707            })
708        },
709    }
710}
711
712fn slice_groups(g: Arc<GroupsType>, offset: i64, len: usize) -> GroupPositions {
713    let sliced = slice_groups_inner(g.as_ref(), offset, len);
714
715    GroupPositions {
716        sliced,
717        original: g,
718        offset,
719        len,
720    }
721}
polars_core/frame/group_by/position.rs

polars_core/frame/group_by/
position.rs
