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Fix: Support for e notation using existing parse_decimal in string to decimal conversion #6905

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Fix: Support for e notation using existing parse_decimal in string to decimal conversion #6905

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8ce814d
add support for e notation in string to decimal using existing parse_…
Dec 18, 2024
4b19083
remove println
Dec 19, 2024
45ec17e
added rounding logic for non e-notation,
Dec 19, 2024
c69b938
add rounding logic for parse_e_notation
Dec 20, 2024
819f0d6
fix csv test case and fix off by one error.
Dec 21, 2024
dd3874d
improved the rounding_digit logic
Dec 21, 2024
460d323
fix parse_decimal for scale=0 case, port over prev tests
Dec 24, 2024
a4f0667
removed unused method parse_string_to_decimal_native and moved over a…
Dec 26, 2024
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168 changes: 10 additions & 158 deletions arrow-cast/src/cast/decimal.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
// under the License.

use crate::cast::*;
use crate::parse::*;

/// A utility trait that provides checked conversions between
/// decimal types inspired by [`NumCast`]
Expand Down Expand Up @@ -230,106 +231,6 @@ where
)?))
}

/// Parses given string to specified decimal native (i128/i256) based on given
/// scale. Returns an `Err` if it cannot parse given string.
pub(crate) fn parse_string_to_decimal_native<T: DecimalType>(
value_str: &str,
scale: usize,
) -> Result<T::Native, ArrowError>
where
T::Native: DecimalCast + ArrowNativeTypeOp,
{
let value_str = value_str.trim();
let parts: Vec<&str> = value_str.split('.').collect();
if parts.len() > 2 {
return Err(ArrowError::InvalidArgumentError(format!(
"Invalid decimal format: {value_str:?}"
)));
}

let (negative, first_part) = if parts[0].is_empty() {
(false, parts[0])
} else {
match parts[0].as_bytes()[0] {
b'-' => (true, &parts[0][1..]),
b'+' => (false, &parts[0][1..]),
_ => (false, parts[0]),
}
};

let integers = first_part;
let decimals = if parts.len() == 2 { parts[1] } else { "" };

if !integers.is_empty() && !integers.as_bytes()[0].is_ascii_digit() {
return Err(ArrowError::InvalidArgumentError(format!(
"Invalid decimal format: {value_str:?}"
)));
}

if !decimals.is_empty() && !decimals.as_bytes()[0].is_ascii_digit() {
return Err(ArrowError::InvalidArgumentError(format!(
"Invalid decimal format: {value_str:?}"
)));
}

// Adjust decimal based on scale
let mut number_decimals = if decimals.len() > scale {
let decimal_number = i256::from_string(decimals).ok_or_else(|| {
ArrowError::InvalidArgumentError(format!("Cannot parse decimal format: {value_str}"))
})?;

let div = i256::from_i128(10_i128).pow_checked((decimals.len() - scale) as u32)?;

let half = div.div_wrapping(i256::from_i128(2));
let half_neg = half.neg_wrapping();

let d = decimal_number.div_wrapping(div);
let r = decimal_number.mod_wrapping(div);

// Round result
let adjusted = match decimal_number >= i256::ZERO {
true if r >= half => d.add_wrapping(i256::ONE),
false if r <= half_neg => d.sub_wrapping(i256::ONE),
_ => d,
};

let integers = if !integers.is_empty() {
i256::from_string(integers)
.ok_or_else(|| {
ArrowError::InvalidArgumentError(format!(
"Cannot parse decimal format: {value_str}"
))
})
.map(|v| v.mul_wrapping(i256::from_i128(10_i128).pow_wrapping(scale as u32)))?
} else {
i256::ZERO
};

format!("{}", integers.add_wrapping(adjusted))
} else {
let padding = if scale > decimals.len() { scale } else { 0 };

let decimals = format!("{decimals:0<padding$}");
format!("{integers}{decimals}")
};

if negative {
number_decimals.insert(0, '-');
}

let value = i256::from_string(number_decimals.as_str()).ok_or_else(|| {
ArrowError::InvalidArgumentError(format!(
"Cannot convert {} to {}: Overflow",
value_str,
T::PREFIX
))
})?;

T::Native::from_decimal(value).ok_or_else(|| {
ArrowError::InvalidArgumentError(format!("Cannot convert {} to {}", value_str, T::PREFIX))
})
}

pub(crate) fn generic_string_to_decimal_cast<'a, T, S>(
from: &'a S,
precision: u8,
Expand All @@ -342,10 +243,9 @@ where
&'a S: StringArrayType<'a>,
{
if cast_options.safe {
let iter = from.iter().map(|v| {
v.and_then(|v| parse_string_to_decimal_native::<T>(v, scale as usize).ok())
.and_then(|v| T::is_valid_decimal_precision(v, precision).then_some(v))
});
let iter = from
.iter()
.map(|v| v.and_then(|v| parse_decimal::<T>(v, precision, scale).ok()));
// Benefit:
// 20% performance improvement
// Soundness:
Expand All @@ -359,15 +259,12 @@ where
.iter()
.map(|v| {
v.map(|v| {
parse_string_to_decimal_native::<T>(v, scale as usize)
.map_err(|_| {
ArrowError::CastError(format!(
"Cannot cast string '{}' to value of {:?} type",
v,
T::DATA_TYPE,
))
})
.and_then(|v| T::validate_decimal_precision(v, precision).map(|_| v))
parse_decimal::<T>(v, precision, scale).map_err(|_| {
ArrowError::CastError(format!(
"Cannot cast string '{}' to decimal type of precision {} and scale {}",
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Contributor Author

Choose a reason for hiding this comment

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T:DATA_TYPE shows default Decimal(38,10) or Decimal256(76,..) in the error message, hiding the precision and scale provided for cast.

v, precision, scale
))
})
})
.transpose()
})
Expand Down Expand Up @@ -622,48 +519,3 @@ where
let array = array.unary::<_, T>(op);
Ok(Arc::new(array))
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn test_parse_string_to_decimal_native() -> Result<(), ArrowError> {
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("0", 0)?,
0_i128
);
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("0", 5)?,
0_i128
);

assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123", 0)?,
123_i128
);
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123", 5)?,
12300000_i128
);

assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.45", 0)?,
123_i128
);
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.45", 5)?,
12345000_i128
);

assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.4567891", 0)?,
123_i128
);
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.4567891", 5)?,
12345679_i128
);
Ok(())
}
}
132 changes: 31 additions & 101 deletions arrow-cast/src/cast/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2501,6 +2501,7 @@ where
#[cfg(test)]
mod tests {
use super::*;
use crate::parse::parse_decimal;
use arrow_buffer::{Buffer, IntervalDayTime, NullBuffer};
use chrono::NaiveDate;
use half::f16;
Expand Down Expand Up @@ -3843,6 +3844,22 @@ mod tests {
}
}
}
#[test]
fn test_cast_with_options_utf8_to_decimal() {
let array = StringArray::from(vec!["4e7"]);
let result = cast_with_options(
&array,
&DataType::Decimal128(10, 2),
&CastOptions {
safe: false,
format_options: FormatOptions::default(),
},
)
.unwrap();
let output_array = result.as_any().downcast_ref::<Decimal128Array>();
let result_128 = parse_decimal::<Decimal128Type>("40000000", 10, 2);
assert_eq!(output_array.unwrap().value(0), result_128.unwrap());
}

#[test]
fn test_cast_utf8_to_bool() {
Expand Down Expand Up @@ -8481,99 +8498,6 @@ mod tests {
);
}

#[test]
fn test_parse_string_to_decimal() {
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>("123.45", 2).unwrap(),
38,
2,
),
"123.45"
);
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>("12345", 2).unwrap(),
38,
2,
),
"12345.00"
);
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>("0.12345", 2).unwrap(),
38,
2,
),
"0.12"
);
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>(".12345", 2).unwrap(),
38,
2,
),
"0.12"
);
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>(".1265", 2).unwrap(),
38,
2,
),
"0.13"
);
assert_eq!(
Decimal128Type::format_decimal(
parse_string_to_decimal_native::<Decimal128Type>(".1265", 2).unwrap(),
38,
2,
),
"0.13"
);

assert_eq!(
Decimal256Type::format_decimal(
parse_string_to_decimal_native::<Decimal256Type>("123.45", 3).unwrap(),
38,
3,
),
"123.450"
);
assert_eq!(
Decimal256Type::format_decimal(
parse_string_to_decimal_native::<Decimal256Type>("12345", 3).unwrap(),
38,
3,
),
"12345.000"
);
assert_eq!(
Decimal256Type::format_decimal(
parse_string_to_decimal_native::<Decimal256Type>("0.12345", 3).unwrap(),
38,
3,
),
"0.123"
);
assert_eq!(
Decimal256Type::format_decimal(
parse_string_to_decimal_native::<Decimal256Type>(".12345", 3).unwrap(),
38,
3,
),
"0.123"
);
assert_eq!(
Decimal256Type::format_decimal(
parse_string_to_decimal_native::<Decimal256Type>(".1265", 3).unwrap(),
38,
3,
),
"0.127"
);
}

fn test_cast_string_to_decimal(array: ArrayRef) {
// Decimal128
let output_type = DataType::Decimal128(38, 2);
Expand Down Expand Up @@ -8832,16 +8756,16 @@ mod tests {
format_options: FormatOptions::default(),
};
let casted_err = cast_with_options(&array, &output_type, &option).unwrap_err();
assert!(casted_err
.to_string()
.contains("Cannot cast string '4.4.5' to value of Decimal128(38, 10) type"));
assert!(casted_err.to_string().contains(
"Cast error: Cannot cast string '4.4.5' to decimal type of precision 38 and scale 2"
));

let str_array = StringArray::from(vec![". 0.123"]);
let array = Arc::new(str_array) as ArrayRef;
let casted_err = cast_with_options(&array, &output_type, &option).unwrap_err();
assert!(casted_err
.to_string()
.contains("Cannot cast string '. 0.123' to value of Decimal128(38, 10) type"));
assert!(casted_err.to_string().contains(
"Cast error: Cannot cast string '. 0.123' to decimal type of precision 38 and scale 2"
));
}

fn test_cast_string_to_decimal128_overflow(overflow_array: ArrayRef) {
Expand Down Expand Up @@ -8885,7 +8809,10 @@ mod tests {
format_options: FormatOptions::default(),
},
);
assert_eq!("Invalid argument error: 100000000000 is too large to store in a Decimal128 of precision 10. Max is 9999999999", err.unwrap_err().to_string());
assert_eq!(
"Cast error: Cannot cast string '1000' to decimal type of precision 10 and scale 8",
err.unwrap_err().to_string()
);
}

#[test]
Expand Down Expand Up @@ -8968,7 +8895,10 @@ mod tests {
format_options: FormatOptions::default(),
},
);
assert_eq!("Invalid argument error: 100000000000 is too large to store in a Decimal256 of precision 10. Max is 9999999999", err.unwrap_err().to_string());
assert_eq!(
"Cast error: Cannot cast string '1000' to decimal type of precision 10 and scale 8",
err.unwrap_err().to_string()
);
}

#[test]
Expand Down
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