vortex_array/arrays/primitive/compute/
cast.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4use vortex_buffer::{Buffer, BufferMut};
5use vortex_dtype::{DType, NativePType, Nullability, match_each_native_ptype};
6use vortex_error::{VortexResult, vortex_bail, vortex_err};
7
8use crate::arrays::PrimitiveVTable;
9use crate::arrays::primitive::PrimitiveArray;
10use crate::compute::{CastKernel, CastKernelAdapter};
11use crate::validity::Validity;
12use crate::vtable::ValidityHelper;
13use crate::{ArrayRef, IntoArray, register_kernel};
14
15impl CastKernel for PrimitiveVTable {
16    fn cast(&self, array: &PrimitiveArray, dtype: &DType) -> VortexResult<Option<ArrayRef>> {
17        let DType::Primitive(new_ptype, new_nullability) = dtype else {
18            return Ok(None);
19        };
20        let (new_ptype, new_nullability) = (*new_ptype, *new_nullability);
21
22        // First, check that the cast is compatible with the source array's validity
23        let new_validity = if array.dtype().nullability() == new_nullability {
24            array.validity().clone()
25        } else if new_nullability == Nullability::Nullable {
26            // from non-nullable to nullable
27            array.validity().clone().into_nullable()
28        } else if new_nullability == Nullability::NonNullable && array.validity().all_valid()? {
29            // from nullable but all valid, to non-nullable
30            Validity::NonNullable
31        } else {
32            vortex_bail!(
33                "invalid cast from nullable to non-nullable, since source array actually contains nulls"
34            );
35        };
36
37        // If the bit width is the same, we can short-circuit and simply update the validity
38        if array.ptype() == new_ptype {
39            return Ok(Some(
40                PrimitiveArray::from_byte_buffer(
41                    array.byte_buffer().clone(),
42                    array.ptype(),
43                    new_validity,
44                )
45                .into_array(),
46            ));
47        }
48
49        // Otherwise, we need to cast the values one-by-one
50        match_each_native_ptype!(new_ptype, |T| {
51            Ok(Some(
52                PrimitiveArray::new(cast::<T>(array)?, new_validity).into_array(),
53            ))
54        })
55    }
56}
57
58register_kernel!(CastKernelAdapter(PrimitiveVTable).lift());
59
60fn cast<T: NativePType>(array: &PrimitiveArray) -> VortexResult<Buffer<T>> {
61    let mut buffer = BufferMut::with_capacity(array.len());
62    match_each_native_ptype!(array.ptype(), |P| {
63        for item in array.as_slice::<P>() {
64            let item = T::from(*item).ok_or_else(
65                || vortex_err!(ComputeError: "Failed to cast {} to {:?}", item, T::PTYPE),
66            )?;
67            // SAFETY: we've pre-allocated the required capacity
68            unsafe { buffer.push_unchecked(item) }
69        }
70    });
71    Ok(buffer.freeze())
72}
73
74#[cfg(test)]
75mod test {
76    use vortex_buffer::buffer;
77    use vortex_dtype::{DType, Nullability, PType};
78    use vortex_error::VortexError;
79
80    use crate::IntoArray;
81    use crate::arrays::PrimitiveArray;
82    use crate::canonical::ToCanonical;
83    use crate::compute::cast;
84    use crate::validity::Validity;
85    use crate::vtable::ValidityHelper;
86
87    #[test]
88    fn cast_u32_u8() {
89        let arr = buffer![0u32, 10, 200].into_array();
90
91        // cast from u32 to u8
92        let p = cast(&arr, PType::U8.into())
93            .unwrap()
94            .to_primitive()
95            .unwrap();
96        assert_eq!(p.as_slice::<u8>(), vec![0u8, 10, 200]);
97        assert_eq!(p.validity(), &Validity::NonNullable);
98
99        // to nullable
100        let p = cast(
101            p.as_ref(),
102            &DType::Primitive(PType::U8, Nullability::Nullable),
103        )
104        .unwrap()
105        .to_primitive()
106        .unwrap();
107        assert_eq!(p.as_slice::<u8>(), vec![0u8, 10, 200]);
108        assert_eq!(p.validity(), &Validity::AllValid);
109
110        // back to non-nullable
111        let p = cast(
112            p.as_ref(),
113            &DType::Primitive(PType::U8, Nullability::NonNullable),
114        )
115        .unwrap()
116        .to_primitive()
117        .unwrap();
118        assert_eq!(p.as_slice::<u8>(), vec![0u8, 10, 200]);
119        assert_eq!(p.validity(), &Validity::NonNullable);
120
121        // to nullable u32
122        let p = cast(
123            p.as_ref(),
124            &DType::Primitive(PType::U32, Nullability::Nullable),
125        )
126        .unwrap()
127        .to_primitive()
128        .unwrap();
129        assert_eq!(p.as_slice::<u32>(), vec![0u32, 10, 200]);
130        assert_eq!(p.validity(), &Validity::AllValid);
131
132        // to non-nullable u8
133        let p = cast(
134            p.as_ref(),
135            &DType::Primitive(PType::U8, Nullability::NonNullable),
136        )
137        .unwrap()
138        .to_primitive()
139        .unwrap();
140        assert_eq!(p.as_slice::<u8>(), vec![0u8, 10, 200]);
141        assert_eq!(p.validity(), &Validity::NonNullable);
142    }
143
144    #[test]
145    fn cast_u32_f32() {
146        let arr = buffer![0u32, 10, 200].into_array();
147        let u8arr = cast(&arr, PType::F32.into())
148            .unwrap()
149            .to_primitive()
150            .unwrap();
151        assert_eq!(u8arr.as_slice::<f32>(), vec![0.0f32, 10., 200.]);
152    }
153
154    #[test]
155    fn cast_i32_u32() {
156        let arr = buffer![-1i32].into_array();
157        let error = cast(&arr, PType::U32.into()).err().unwrap();
158        let VortexError::ComputeError(s, _) = error else {
159            unreachable!()
160        };
161        assert_eq!(s.to_string(), "Failed to cast -1 to U32");
162    }
163
164    #[test]
165    fn cast_array_with_nulls_to_nonnullable() {
166        let arr = PrimitiveArray::from_option_iter([Some(-1i32), None, Some(10)]);
167        let err = cast(arr.as_ref(), PType::I32.into()).unwrap_err();
168        let VortexError::InvalidArgument(s, _) = err else {
169            unreachable!()
170        };
171        assert_eq!(
172            s.to_string(),
173            "invalid cast from nullable to non-nullable, since source array actually contains nulls"
174        );
175    }
176}
vortex_array/arrays/primitive/compute/cast.rs

vortex_array/arrays/primitive/compute/
cast.rs
