vortex_array/arrays/chunked/
decode.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4use vortex_buffer::BufferMut;
5use vortex_dtype::{DType, Nullability, PType, StructFields};
6use vortex_error::{VortexExpect, VortexResult, vortex_err};
7
8use super::ChunkedArray;
9use crate::arrays::{ChunkedVTable, ListArray, PrimitiveArray, StructArray};
10use crate::builders::{ArrayBuilder, builder_with_capacity};
11use crate::compute::cast;
12use crate::validity::Validity;
13use crate::vtable::CanonicalVTable;
14use crate::{Array as _, ArrayRef, Canonical, IntoArray, ToCanonical};
15
16impl CanonicalVTable<ChunkedVTable> for ChunkedVTable {
17    fn canonicalize(array: &ChunkedArray) -> VortexResult<Canonical> {
18        if array.nchunks() == 0 {
19            return Ok(Canonical::empty(array.dtype()));
20        }
21        if array.nchunks() == 1 {
22            return array.chunks()[0].to_canonical();
23        }
24
25        match array.dtype() {
26            DType::Struct(struct_dtype, _) => {
27                let struct_array = swizzle_struct_chunks(
28                    array.chunks(),
29                    Validity::copy_from_array(array.as_ref())?,
30                    struct_dtype,
31                )?;
32                Ok(Canonical::Struct(struct_array))
33            }
34            DType::List(elem_dtype, _) => Ok(Canonical::List(pack_lists(
35                array.chunks(),
36                Validity::copy_from_array(array.as_ref())?,
37                elem_dtype,
38            )?)),
39            _ => {
40                let mut builder = builder_with_capacity(array.dtype(), array.len());
41                array.append_to_builder(builder.as_mut())?;
42                builder.finish().to_canonical()
43            }
44        }
45    }
46
47    fn append_to_builder(array: &ChunkedArray, builder: &mut dyn ArrayBuilder) -> VortexResult<()> {
48        for chunk in array.chunks() {
49            chunk.append_to_builder(builder)?;
50        }
51        Ok(())
52    }
53}
54
55/// Swizzle the pointers within a ChunkedArray of StructArrays to instead be a single
56/// StructArray, where the Array for each Field is a ChunkedArray.
57fn swizzle_struct_chunks(
58    chunks: &[ArrayRef],
59    validity: Validity,
60    struct_dtype: &StructFields,
61) -> VortexResult<StructArray> {
62    let len = chunks.iter().map(|chunk| chunk.len()).sum();
63    let mut field_arrays = Vec::new();
64
65    for (field_idx, field_dtype) in struct_dtype.fields().enumerate() {
66        let field_chunks = chunks
67            .iter()
68            .map(|c| {
69                c.to_struct()
70                    .vortex_expect("Chunk was not a StructArray")
71                    .fields()
72                    .get(field_idx)
73                    .vortex_expect("Invalid field index")
74                    .to_array()
75            })
76            .collect::<Vec<_>>();
77        let field_array = ChunkedArray::try_new(field_chunks, field_dtype.clone())?;
78        field_arrays.push(field_array.into_array());
79    }
80
81    StructArray::try_new_with_dtype(field_arrays, struct_dtype.clone(), len, validity)
82}
83
84fn pack_lists(
85    chunks: &[ArrayRef],
86    validity: Validity,
87    elem_dtype: &DType,
88) -> VortexResult<ListArray> {
89    let len: usize = chunks.iter().map(|c| c.len()).sum();
90    let mut offsets = BufferMut::<i64>::with_capacity(len + 1);
91    offsets.push(0);
92    let mut elements = Vec::new();
93
94    for chunk in chunks {
95        let chunk = chunk.to_list()?;
96        // TODO: handle i32 offsets if they fit.
97        let offsets_arr = cast(
98            chunk.offsets(),
99            &DType::Primitive(PType::I64, Nullability::NonNullable),
100        )?
101        .to_primitive()?;
102
103        let first_offset_value: usize = usize::try_from(&offsets_arr.scalar_at(0))?;
104        let last_offset_value: usize =
105            usize::try_from(&offsets_arr.scalar_at(offsets_arr.len() - 1))?;
106        elements.push(
107            chunk
108                .elements()
109                .slice(first_offset_value, last_offset_value),
110        );
111
112        let adjustment_from_previous = *offsets
113            .last()
114            .ok_or_else(|| vortex_err!("List offsets must have at least one element"))?;
115        offsets.extend_trusted(
116            offsets_arr
117                .as_slice::<i64>()
118                .iter()
119                .skip(1)
120                .map(|off| off + adjustment_from_previous - first_offset_value as i64),
121        );
122    }
123    let chunked_elements = ChunkedArray::try_new(elements, elem_dtype.clone())?.into_array();
124    let offsets = PrimitiveArray::new(offsets.freeze(), Validity::NonNullable);
125
126    ListArray::try_new(chunked_elements, offsets.into_array(), validity)
127}
128
129#[cfg(test)]
130mod tests {
131    use std::sync::Arc;
132
133    use vortex_dtype::DType::{List, Primitive};
134    use vortex_dtype::Nullability::NonNullable;
135    use vortex_dtype::PType::I32;
136
137    use crate::accessor::ArrayAccessor;
138    use crate::arrays::{ChunkedArray, ListArray, PrimitiveArray, StructArray, VarBinViewArray};
139    use crate::validity::Validity;
140    use crate::{IntoArray, ToCanonical};
141
142    #[test]
143    pub fn pack_nested_structs() {
144        let struct_array = StructArray::try_new(
145            vec!["a".into()].into(),
146            vec![VarBinViewArray::from_iter_str(["foo", "bar", "baz", "quak"]).into_array()],
147            4,
148            Validity::NonNullable,
149        )
150        .unwrap();
151        let dtype = struct_array.dtype().clone();
152        let chunked = ChunkedArray::try_new(
153            vec![
154                ChunkedArray::try_new(vec![struct_array.to_array()], dtype.clone())
155                    .unwrap()
156                    .into_array(),
157            ],
158            dtype,
159        )
160        .unwrap()
161        .into_array();
162        let canonical_struct = chunked.to_struct().unwrap();
163        let canonical_varbin = canonical_struct.fields()[0].to_varbinview().unwrap();
164        let original_varbin = struct_array.fields()[0].to_varbinview().unwrap();
165        let orig_values = original_varbin
166            .with_iterator(|it| it.map(|a| a.map(|v| v.to_vec())).collect::<Vec<_>>())
167            .unwrap();
168        let canon_values = canonical_varbin
169            .with_iterator(|it| it.map(|a| a.map(|v| v.to_vec())).collect::<Vec<_>>())
170            .unwrap();
171        assert_eq!(orig_values, canon_values);
172    }
173
174    #[test]
175    pub fn pack_nested_lists() {
176        let l1 = ListArray::try_new(
177            PrimitiveArray::from_iter([1, 2, 3, 4]).into_array(),
178            PrimitiveArray::from_iter([0, 3]).into_array(),
179            Validity::NonNullable,
180        )
181        .unwrap();
182
183        let l2 = ListArray::try_new(
184            PrimitiveArray::from_iter([5, 6]).into_array(),
185            PrimitiveArray::from_iter([0, 2]).into_array(),
186            Validity::NonNullable,
187        )
188        .unwrap();
189
190        let chunked_list = ChunkedArray::try_new(
191            vec![l1.clone().into_array(), l2.clone().into_array()],
192            List(Arc::new(Primitive(I32, NonNullable)), NonNullable),
193        );
194
195        let canon_values = chunked_list.unwrap().to_list().unwrap();
196
197        assert_eq!(l1.scalar_at(0), canon_values.scalar_at(0));
198        assert_eq!(l2.scalar_at(0), canon_values.scalar_at(1));
199    }
200}
vortex_array/arrays/chunked/decode.rs

vortex_array/arrays/chunked/
decode.rs
