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//! Defines the division arithmetic kernels for Decimal
//! `PrimitiveArrays`.
use crate::{
array::PrimitiveArray,
compute::{
arithmetics::{ArrayCheckedDiv, ArrayDiv},
arity::{binary, binary_checked, unary},
utils::{check_same_len, combine_validities},
},
datatypes::DataType,
error::{Error, Result},
scalar::{PrimitiveScalar, Scalar},
};
use super::{adjusted_precision_scale, get_parameters, max_value, number_digits};
/// Divide two decimal primitive arrays with the same precision and scale. If
/// the precision and scale is different, then an InvalidArgumentError is
/// returned. This function panics if the dividend is divided by 0 or None.
/// This function also panics if the division produces a number larger
/// than the possible number for the array precision.
///
/// # Examples
/// ```
/// use arrow2::compute::arithmetics::decimal::div;
/// use arrow2::array::PrimitiveArray;
/// use arrow2::datatypes::DataType;
///
/// let a = PrimitiveArray::from([Some(1_00i128), Some(4_00i128), Some(6_00i128)]).to(DataType::Decimal(5, 2));
/// let b = PrimitiveArray::from([Some(1_00i128), Some(2_00i128), Some(2_00i128)]).to(DataType::Decimal(5, 2));
///
/// let result = div(&a, &b);
/// let expected = PrimitiveArray::from([Some(1_00i128), Some(2_00i128), Some(3_00i128)]).to(DataType::Decimal(5, 2));
///
/// assert_eq!(result, expected);
/// ```
pub fn div(lhs: &PrimitiveArray<i128>, rhs: &PrimitiveArray<i128>) -> PrimitiveArray<i128> {
let (precision, scale) = get_parameters(lhs.data_type(), rhs.data_type()).unwrap();
let scale = 10i128.pow(scale as u32);
let max = max_value(precision);
let op = move |a: i128, b: i128| {
// The division is done using the numbers without scale.
// The dividend is scaled up to maintain precision after the
// division
// 222.222 --> 222222000
// 123.456 --> 123456
// -------- ---------
// 1.800 <-- 1800
let numeral: i128 = a * scale;
// The division can overflow if the dividend is divided
// by zero.
let res: i128 = numeral.checked_div(b).expect("Found division by zero");
assert!(
res.abs() <= max,
"Overflow in multiplication presented for precision {}",
precision
);
res
};
binary(lhs, rhs, lhs.data_type().clone(), op)
}
/// Multiply a decimal [`PrimitiveArray`] with a [`PrimitiveScalar`] with the same precision and scale. If
/// the precision and scale is different, then an InvalidArgumentError is
/// returned. This function panics if the multiplied numbers result in a number
/// larger than the possible number for the selected precision.
pub fn div_scalar(lhs: &PrimitiveArray<i128>, rhs: &PrimitiveScalar<i128>) -> PrimitiveArray<i128> {
let (precision, scale) = get_parameters(lhs.data_type(), rhs.data_type()).unwrap();
let rhs = if let Some(rhs) = *rhs.value() {
rhs
} else {
return PrimitiveArray::<i128>::new_null(lhs.data_type().clone(), lhs.len());
};
let scale = 10i128.pow(scale as u32);
let max = max_value(precision);
let op = move |a: i128| {
// The division is done using the numbers without scale.
// The dividend is scaled up to maintain precision after the
// division
// 222.222 --> 222222000
// 123.456 --> 123456
// -------- ---------
// 1.800 <-- 1800
let numeral: i128 = a * scale;
// The division can overflow if the dividend is divided
// by zero.
let res: i128 = numeral.checked_div(rhs).expect("Found division by zero");
assert!(
res.abs() <= max,
"Overflow in multiplication presented for precision {}",
precision
);
res
};
unary(lhs, op, lhs.data_type().clone())
}
/// Saturated division of two decimal primitive arrays with the same
/// precision and scale. If the precision and scale is different, then an
/// InvalidArgumentError is returned. If the result from the division is
/// larger than the possible number with the selected precision then the
/// resulted number in the arrow array is the maximum number for the selected
/// precision. The function panics if divided by zero.
///
/// # Examples
/// ```
/// use arrow2::compute::arithmetics::decimal::saturating_div;
/// use arrow2::array::PrimitiveArray;
/// use arrow2::datatypes::DataType;
///
/// let a = PrimitiveArray::from([Some(999_99i128), Some(4_00i128), Some(6_00i128)]).to(DataType::Decimal(5, 2));
/// let b = PrimitiveArray::from([Some(000_01i128), Some(2_00i128), Some(2_00i128)]).to(DataType::Decimal(5, 2));
///
/// let result = saturating_div(&a, &b);
/// let expected = PrimitiveArray::from([Some(999_99i128), Some(2_00i128), Some(3_00i128)]).to(DataType::Decimal(5, 2));
///
/// assert_eq!(result, expected);
/// ```
pub fn saturating_div(
lhs: &PrimitiveArray<i128>,
rhs: &PrimitiveArray<i128>,
) -> PrimitiveArray<i128> {
let (precision, scale) = get_parameters(lhs.data_type(), rhs.data_type()).unwrap();
let scale = 10i128.pow(scale as u32);
let max = max_value(precision);
let op = move |a: i128, b: i128| {
let numeral: i128 = a * scale;
match numeral.checked_div(b) {
Some(res) => match res {
res if res.abs() > max => {
if res > 0 {
max
} else {
-max
}
}
_ => res,
},
None => 0,
}
};
binary(lhs, rhs, lhs.data_type().clone(), op)
}
/// Checked division of two decimal primitive arrays with the same precision
/// and scale. If the precision and scale is different, then an
/// InvalidArgumentError is returned. If the divisor is zero, then the
/// validity for that index is changed to None
///
/// # Examples
/// ```
/// use arrow2::compute::arithmetics::decimal::checked_div;
/// use arrow2::array::PrimitiveArray;
/// use arrow2::datatypes::DataType;
///
/// let a = PrimitiveArray::from([Some(1_00i128), Some(4_00i128), Some(6_00i128)]).to(DataType::Decimal(5, 2));
/// let b = PrimitiveArray::from([Some(000_00i128), None, Some(2_00i128)]).to(DataType::Decimal(5, 2));
///
/// let result = checked_div(&a, &b);
/// let expected = PrimitiveArray::from([None, None, Some(3_00i128)]).to(DataType::Decimal(5, 2));
///
/// assert_eq!(result, expected);
/// ```
pub fn checked_div(lhs: &PrimitiveArray<i128>, rhs: &PrimitiveArray<i128>) -> PrimitiveArray<i128> {
let (precision, scale) = get_parameters(lhs.data_type(), rhs.data_type()).unwrap();
let scale = 10i128.pow(scale as u32);
let max = max_value(precision);
let op = move |a: i128, b: i128| {
let numeral: i128 = a * scale;
match numeral.checked_div(b) {
Some(res) => match res {
res if res.abs() > max => None,
_ => Some(res),
},
None => None,
}
};
binary_checked(lhs, rhs, lhs.data_type().clone(), op)
}
// Implementation of ArrayDiv trait for PrimitiveArrays
impl ArrayDiv<PrimitiveArray<i128>> for PrimitiveArray<i128> {
fn div(&self, rhs: &PrimitiveArray<i128>) -> Self {
div(self, rhs)
}
}
// Implementation of ArrayCheckedDiv trait for PrimitiveArrays
impl ArrayCheckedDiv<PrimitiveArray<i128>> for PrimitiveArray<i128> {
fn checked_div(&self, rhs: &PrimitiveArray<i128>) -> Self {
checked_div(self, rhs)
}
}
/// Adaptive division of two decimal primitive arrays with different precision
/// and scale. If the precision and scale is different, then the smallest scale
/// and precision is adjusted to the largest precision and scale. If during the
/// division one of the results is larger than the max possible value, the
/// result precision is changed to the precision of the max value. The function
/// panics when divided by zero.
///
/// ```nocode
/// 1000.00 -> 7, 2
/// 10.0000 -> 6, 4
/// -----------------
/// 100.0000 -> 9, 4
/// ```
/// # Examples
/// ```
/// use arrow2::compute::arithmetics::decimal::adaptive_div;
/// use arrow2::array::PrimitiveArray;
/// use arrow2::datatypes::DataType;
///
/// let a = PrimitiveArray::from([Some(1000_00i128)]).to(DataType::Decimal(7, 2));
/// let b = PrimitiveArray::from([Some(10_0000i128)]).to(DataType::Decimal(6, 4));
/// let result = adaptive_div(&a, &b).unwrap();
/// let expected = PrimitiveArray::from([Some(100_0000i128)]).to(DataType::Decimal(9, 4));
///
/// assert_eq!(result, expected);
/// ```
pub fn adaptive_div(
lhs: &PrimitiveArray<i128>,
rhs: &PrimitiveArray<i128>,
) -> Result<PrimitiveArray<i128>> {
check_same_len(lhs, rhs)?;
let (lhs_p, lhs_s, rhs_p, rhs_s) =
if let (DataType::Decimal(lhs_p, lhs_s), DataType::Decimal(rhs_p, rhs_s)) =
(lhs.data_type(), rhs.data_type())
{
(*lhs_p, *lhs_s, *rhs_p, *rhs_s)
} else {
return Err(Error::InvalidArgumentError(
"Incorrect data type for the array".to_string(),
));
};
// The resulting precision is mutable because it could change while
// looping through the iterator
let (mut res_p, res_s, diff) = adjusted_precision_scale(lhs_p, lhs_s, rhs_p, rhs_s);
let shift = 10i128.pow(diff as u32);
let shift_1 = 10i128.pow(res_s as u32);
let mut max = max_value(res_p);
let values = lhs
.values()
.iter()
.zip(rhs.values().iter())
.map(|(l, r)| {
let numeral: i128 = l * shift_1;
// Based on the array's scales one of the arguments in the sum has to be shifted
// to the left to match the final scale
let res = if lhs_s > rhs_s {
numeral.checked_div(r * shift)
} else {
(numeral * shift).checked_div(*r)
}
.expect("Found division by zero");
// The precision of the resulting array will change if one of the
// multiplications during the iteration produces a value bigger
// than the possible value for the initial precision
// 10.0000 -> 6, 4
// 00.1000 -> 6, 4
// -----------------
// 100.0000 -> 7, 4
if res.abs() > max {
res_p = number_digits(res);
max = max_value(res_p);
}
res
})
.collect::<Vec<_>>();
let validity = combine_validities(lhs.validity(), rhs.validity());
Ok(PrimitiveArray::<i128>::new(
DataType::Decimal(res_p, res_s),
values.into(),
validity,
))
}