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Use ArrayAccessor and FromIterator in Cast Kernels #2169

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merged 3 commits into from Jul 27, 2022
Merged

Use ArrayAccessor and FromIterator in Cast Kernels #2169

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e725bd1
Use ArrayAccessor
viirya Jul 25, 2022
c775d60
Add to_i128 and to_f64 to ArrowNumericType
viirya Jul 26, 2022
3ca4911
Use AsPrimitive
viirya Jul 27, 2022
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140 changes: 84 additions & 56 deletions arrow/src/compute/kernels/cast.rs
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Expand Up @@ -38,7 +38,6 @@
use std::str;
use std::sync::Arc;

use crate::array::BasicDecimalArray;
use crate::buffer::MutableBuffer;
use crate::compute::divide_scalar;
use crate::compute::kernels::arithmetic::{divide, multiply};
Expand Down Expand Up @@ -270,45 +269,62 @@ pub fn cast(array: &ArrayRef, to_type: &DataType) -> Result<ArrayRef> {
cast_with_options(array, to_type, &DEFAULT_CAST_OPTIONS)
}

// cast the integer array to defined decimal data type array
macro_rules! cast_integer_to_decimal {
($ARRAY: expr, $ARRAY_TYPE: ident, $PRECISION : ident, $SCALE : ident) => {{
let array = $ARRAY.as_any().downcast_ref::<$ARRAY_TYPE>().unwrap();
let mul: i128 = 10_i128.pow(*$SCALE as u32);
let decimal_array = array
.iter()
.map(|v| {
v.map(|v| {
let v = v as i128;
// with_precision_and_scale validates the
// value is within range for the output precision
mul * v
})
})
.collect::<Decimal128Array>()
.with_precision_and_scale(*$PRECISION, *$SCALE)?;
Ok(Arc::new(decimal_array))
}};
/// Cast the primitive array to defined decimal data type array
fn cast_primitive_to_decimal<T: ArrayAccessor, F>(
array: T,
op: F,
precision: usize,
scale: usize,
) -> Result<Arc<dyn Array>>
where
F: Fn(T::Item) -> i128,
{
#[allow(clippy::redundant_closure)]
let decimal_array = ArrayIter::new(array)
.map(|v| v.map(|v| op(v)))
.collect::<Decimal128Array>()
.with_precision_and_scale(precision, scale)?;

Ok(Arc::new(decimal_array))
}

// cast the floating-point array to defined decimal data type array
macro_rules! cast_floating_point_to_decimal {
($ARRAY: expr, $ARRAY_TYPE: ident, $PRECISION : ident, $SCALE : ident) => {{
let array = $ARRAY.as_any().downcast_ref::<$ARRAY_TYPE>().unwrap();
let mul = 10_f64.powi(*$SCALE as i32);
let decimal_array = array
.iter()
.map(|v| {
v.map(|v| {
// with_precision_and_scale validates the
// value is within range for the output precision
((v as f64) * mul) as i128
})
})
.collect::<Decimal128Array>()
.with_precision_and_scale(*$PRECISION, *$SCALE)?;
Ok(Arc::new(decimal_array))
}};
fn cast_integer_to_decimal<T: ArrowNumericType>(
array: &PrimitiveArray<T>,
precision: usize,
scale: usize,
) -> Result<Arc<dyn Array>> {
let mul: i128 = 10_i128.pow(scale as u32);

// with_precision_and_scale validates the
// value is within range for the output precision
cast_primitive_to_decimal(
array,
|v| v.to_isize().unwrap() as i128 * mul,
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Same here

precision,
scale,
)
}

fn cast_floating_point_to_decimal<T: ArrowNumericType>(
array: &PrimitiveArray<T>,
precision: usize,
scale: usize,
) -> Result<Arc<dyn Array>>
where
<T as ArrowPrimitiveType>::Native: ToPrimitive,
{
let mul = 10_f64.powi(scale as i32);

cast_primitive_to_decimal(
array,
|v| {
// with_precision_and_scale validates the
// value is within range for the output precision
((num::ToPrimitive::to_f64(&v).unwrap()) * mul) as i128
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I think this is now a checked conversion where previously it wasn't?

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Hmm, but I cannot use v as f64 here.

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error[E0605]: non-primitive cast: `<T as native::ArrowPrimitiveType>::Native` as `i128`
   --> arrow/src/compute/kernels/cast.rs:300:42
    |
300 |     cast_primitive_to_decimal(array, |v| v as i128 * mul, precision, scale)
    |                                          ^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object

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Added helper functions to ArrowPrimitiveType.

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Why not use AsPrimitive instead of ToPrimitive?

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Ah, good suggestion.

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I'm not aware of AsPrimitive trait.

},
precision,
scale,
)
}

// cast the decimal array to integer array
Expand Down Expand Up @@ -428,24 +444,36 @@ pub fn cast_with_options(
// cast data to decimal
match from_type {
// TODO now just support signed numeric to decimal, support decimal to numeric later
Int8 => {
cast_integer_to_decimal!(array, Int8Array, precision, scale)
}
Int16 => {
cast_integer_to_decimal!(array, Int16Array, precision, scale)
}
Int32 => {
cast_integer_to_decimal!(array, Int32Array, precision, scale)
}
Int64 => {
cast_integer_to_decimal!(array, Int64Array, precision, scale)
}
Float32 => {
cast_floating_point_to_decimal!(array, Float32Array, precision, scale)
}
Float64 => {
cast_floating_point_to_decimal!(array, Float64Array, precision, scale)
}
Int8 => cast_integer_to_decimal(
as_primitive_array::<Int8Type>(array),
*precision,
*scale,
),
Int16 => cast_integer_to_decimal(
as_primitive_array::<Int16Type>(array),
*precision,
*scale,
),
Int32 => cast_integer_to_decimal(
as_primitive_array::<Int32Type>(array),
*precision,
*scale,
),
Int64 => cast_integer_to_decimal(
as_primitive_array::<Int64Type>(array),
*precision,
*scale,
),
Float32 => cast_floating_point_to_decimal(
as_primitive_array::<Float32Type>(array),
*precision,
*scale,
),
Float64 => cast_floating_point_to_decimal(
as_primitive_array::<Float64Type>(array),
*precision,
*scale,
),
Null => Ok(new_null_array(to_type, array.len())),
_ => Err(ArrowError::CastError(format!(
"Casting from {:?} to {:?} not supported",
Expand Down