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38 changes: 35 additions & 3 deletions arrow-string/src/length.rs
Original file line number Diff line number Diff line change
Expand Up @@ -19,8 +19,9 @@

use arrow_array::*;
use arrow_array::{cast::AsArray, types::*};
use arrow_buffer::{ArrowNativeType, NullBuffer, OffsetBuffer};
use arrow_buffer::{ArrowNativeType, NullBuffer, OffsetBuffer, ScalarBuffer};
use arrow_schema::{ArrowError, DataType};
use cast::as_string_array;
use std::sync::Arc;

fn length_impl<P: ArrowPrimitiveType>(
Expand Down Expand Up @@ -137,6 +138,22 @@ pub fn bit_length(array: &dyn Array) -> Result<ArrayRef, ArrowError> {
let list = array.as_string::<i64>();
Ok(bit_length_impl::<Int64Type>(list.offsets(), list.nulls()))
}
DataType::Utf8View => {
let list = array.as_string_view();
let values = (0..list.len())
.map(|i| {
if list.is_valid(i) {
list.views()[i] as u32 * 8
} else {
0
}
})
.collect::<Vec<u32>>();
Ok(Arc::new(UInt32Array::new(
values.into(),
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@tustvold tustvold Nov 4, 2024

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Suggested change
let values = (0..list.len())
.map(|i| {
if list.is_valid(i) {
list.views()[i] as u32 * 8
} else {
0
}
})
.collect::<Vec<u32>>();
Ok(Arc::new(UInt32Array::new(
values.into(),
let values = list.views().iter().map(|view| (view as i32).wrapping_mul(8)).collect();
Ok(Arc::new(Int32Array::new(
values,

As we're doing infallible wrapping arithmetic, we can just compute this for everything, this will vectorize better, and the null mask is preserved below

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@austin362667 austin362667 Nov 4, 2024

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Wow! Thank you so much @tustvold , you are indeed making me a better Rust programmer. Really appreciate for review. 👍

array.nulls().cloned(),
)))
}
DataType::Binary => {
let list = array.as_binary::<i32>();
Ok(bit_length_impl::<Int32Type>(list.offsets(), list.nulls()))
Expand Down Expand Up @@ -418,7 +435,7 @@ mod tests {
assert_eq!(&expected, result);
}

fn bit_length_cases() -> Vec<(Vec<&'static str>, usize, Vec<i32>)> {
fn bit_length_cases() -> Vec<(Vec<&'static str>, usize, Vec<u32>)> {
// a large array
let values = ["one", "on", "o", ""];
let values = values.into_iter().cycle().take(4096).collect();
Expand All @@ -440,7 +457,7 @@ mod tests {
let array = StringArray::from(input);
let result = bit_length(&array).unwrap();
assert_eq!(len, result.len());
let result = result.as_any().downcast_ref::<Int32Array>().unwrap();
let result = result.as_any().downcast_ref::<UInt32Array>().unwrap();
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I agree that bit_length should not beed to return signed integer, but it seems better not to change this within this PR.

expected.iter().enumerate().for_each(|(i, value)| {
assert_eq!(*value, result.value(i));
});
Expand All @@ -462,6 +479,21 @@ mod tests {
})
}

#[test]
fn bit_length_test_utf8view() {
bit_length_cases()
.into_iter()
.for_each(|(input, len, expected)| {
let string_array = StringViewArray::from(input);
let result = bit_length(&string_array).unwrap();
assert_eq!(len, result.len());
let result = result.as_any().downcast_ref::<UInt32Array>().unwrap();
expected.iter().enumerate().for_each(|(i, value)| {
assert_eq!(*value, result.value(i));
});
})
}

#[test]
fn bit_length_binary() {
let value: Vec<&[u8]> = vec![b"one", &[0xff, 0xf8], b"three"];
Expand Down