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sort.rs
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sort.rs
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
//! Defines sort kernel for `ArrayRef`
use crate::array::*;
use crate::buffer::MutableBuffer;
use crate::compute::take;
use crate::datatypes::*;
use crate::error::{ArrowError, Result};
use std::cmp::Ordering;
use TimeUnit::*;
/// Sort the `ArrayRef` using `SortOptions`.
///
/// Performs a sort on values and indices. Nulls are ordered according
/// to the `nulls_first` flag in `options`. Floats are sorted using
/// IEEE 754 totalOrder
///
/// Returns an `ArrowError::ComputeError(String)` if the array type is
/// either unsupported by `sort_to_indices` or `take`.
///
/// Note: this is an unstable_sort, meaning it may not preserve the
/// order of equal elements.
///
/// # Example
/// ```rust
/// # use std::sync::Arc;
/// # use arrow::array::{Int32Array, ArrayRef};
/// # use arrow::error::Result;
/// # use arrow::compute::kernels::sort::sort;
/// # fn main() -> Result<()> {
/// let array: ArrayRef = Arc::new(Int32Array::from(vec![5, 4, 3, 2, 1]));
/// let sorted_array = sort(&array, None).unwrap();
/// let sorted_array = sorted_array.as_any().downcast_ref::<Int32Array>().unwrap();
/// assert_eq!(sorted_array, &Int32Array::from(vec![1, 2, 3, 4, 5]));
/// # Ok(())
/// # }
/// ```
pub fn sort(values: &ArrayRef, options: Option<SortOptions>) -> Result<ArrayRef> {
let indices = sort_to_indices(values, options, None)?;
take(values.as_ref(), &indices, None)
}
/// Sort the `ArrayRef` partially.
///
/// If `limit` is specified, the resulting array will contain only
/// first `limit` in the sort order. Any data data after the limit
/// will be discarded.
///
/// Note: this is an unstable_sort, meaning it may not preserve the
/// order of equal elements.
///
/// # Example
/// ```rust
/// # use std::sync::Arc;
/// # use arrow::array::{Int32Array, ArrayRef};
/// # use arrow::error::Result;
/// # use arrow::compute::kernels::sort::{sort_limit, SortOptions};
/// # fn main() -> Result<()> {
/// let array: ArrayRef = Arc::new(Int32Array::from(vec![5, 4, 3, 2, 1]));
///
/// // Find the the top 2 items
/// let sorted_array = sort_limit(&array, None, Some(2)).unwrap();
/// let sorted_array = sorted_array.as_any().downcast_ref::<Int32Array>().unwrap();
/// assert_eq!(sorted_array, &Int32Array::from(vec![1, 2]));
///
/// // Find the bottom top 2 items
/// let options = Some(SortOptions {
/// descending: true,
/// ..Default::default()
/// });
/// let sorted_array = sort_limit(&array, options, Some(2)).unwrap();
/// let sorted_array = sorted_array.as_any().downcast_ref::<Int32Array>().unwrap();
/// assert_eq!(sorted_array, &Int32Array::from(vec![5, 4]));
/// # Ok(())
/// # }
/// ```
pub fn sort_limit(
values: &ArrayRef,
options: Option<SortOptions>,
limit: Option<usize>,
) -> Result<ArrayRef> {
let indices = sort_to_indices(values, options, limit)?;
take(values.as_ref(), &indices, None)
}
/// we can only do this if the T is primitive
#[inline]
fn sort_unstable_by<T, F>(array: &mut [T], limit: usize, cmp: F)
where
F: FnMut(&T, &T) -> Ordering,
{
if array.len() == limit {
array.sort_unstable_by(cmp);
} else {
partial_sort(array, limit, cmp);
}
}
// implements comparison using IEEE 754 total ordering for f32
// Original implementation from https://doc.rust-lang.org/std/primitive.f64.html#method.total_cmp
// TODO to change to use std when it becomes stable
fn total_cmp_32(l: f32, r: f32) -> std::cmp::Ordering {
let mut left = l.to_bits() as i32;
let mut right = r.to_bits() as i32;
left ^= (((left >> 31) as u32) >> 1) as i32;
right ^= (((right >> 31) as u32) >> 1) as i32;
left.cmp(&right)
}
// implements comparison using IEEE 754 total ordering for f64
// Original implementation from https://doc.rust-lang.org/std/primitive.f64.html#method.total_cmp
// TODO to change to use std when it becomes stable
fn total_cmp_64(l: f64, r: f64) -> std::cmp::Ordering {
let mut left = l.to_bits() as i64;
let mut right = r.to_bits() as i64;
left ^= (((left >> 63) as u64) >> 1) as i64;
right ^= (((right >> 63) as u64) >> 1) as i64;
left.cmp(&right)
}
fn cmp<T>(l: T, r: T) -> std::cmp::Ordering
where
T: Ord,
{
l.cmp(&r)
}
// partition indices into valid and null indices
fn partition_validity(array: &ArrayRef) -> (Vec<u32>, Vec<u32>) {
match array.null_count() {
// faster path
0 => ((0..(array.len() as u32)).collect(), vec![]),
_ => {
let indices = 0..(array.len() as u32);
indices.partition(|index| array.is_valid(*index as usize))
}
}
}
/// Sort elements from `ArrayRef` into an unsigned integer (`UInt32Array`) of indices.
/// For floating point arrays any NaN values are considered to be greater than any other non-null value
/// limit is an option for partial_sort
pub fn sort_to_indices(
values: &ArrayRef,
options: Option<SortOptions>,
limit: Option<usize>,
) -> Result<UInt32Array> {
let options = options.unwrap_or_default();
let (v, n) = partition_validity(values);
Ok(match values.data_type() {
DataType::Boolean => sort_boolean(values, v, n, &options, limit),
DataType::Int8 => {
sort_primitive::<Int8Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Int16 => {
sort_primitive::<Int16Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Int32 => {
sort_primitive::<Int32Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Int64 => {
sort_primitive::<Int64Type, _>(values, v, n, cmp, &options, limit)
}
DataType::UInt8 => {
sort_primitive::<UInt8Type, _>(values, v, n, cmp, &options, limit)
}
DataType::UInt16 => {
sort_primitive::<UInt16Type, _>(values, v, n, cmp, &options, limit)
}
DataType::UInt32 => {
sort_primitive::<UInt32Type, _>(values, v, n, cmp, &options, limit)
}
DataType::UInt64 => {
sort_primitive::<UInt64Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Float32 => {
sort_primitive::<Float32Type, _>(values, v, n, total_cmp_32, &options, limit)
}
DataType::Float64 => {
sort_primitive::<Float64Type, _>(values, v, n, total_cmp_64, &options, limit)
}
DataType::Date32 => {
sort_primitive::<Date32Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Date64 => {
sort_primitive::<Date64Type, _>(values, v, n, cmp, &options, limit)
}
DataType::Time32(Second) => {
sort_primitive::<Time32SecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Time32(Millisecond) => {
sort_primitive::<Time32MillisecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Time64(Microsecond) => {
sort_primitive::<Time64MicrosecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Time64(Nanosecond) => {
sort_primitive::<Time64NanosecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Timestamp(Second, _) => {
sort_primitive::<TimestampSecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Timestamp(Millisecond, _) => {
sort_primitive::<TimestampMillisecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Timestamp(Microsecond, _) => {
sort_primitive::<TimestampMicrosecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Timestamp(Nanosecond, _) => {
sort_primitive::<TimestampNanosecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Interval(IntervalUnit::YearMonth) => {
sort_primitive::<IntervalYearMonthType, _>(values, v, n, cmp, &options, limit)
}
DataType::Interval(IntervalUnit::DayTime) => {
sort_primitive::<IntervalDayTimeType, _>(values, v, n, cmp, &options, limit)
}
DataType::Duration(TimeUnit::Second) => {
sort_primitive::<DurationSecondType, _>(values, v, n, cmp, &options, limit)
}
DataType::Duration(TimeUnit::Millisecond) => {
sort_primitive::<DurationMillisecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Duration(TimeUnit::Microsecond) => {
sort_primitive::<DurationMicrosecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Duration(TimeUnit::Nanosecond) => {
sort_primitive::<DurationNanosecondType, _>(
values, v, n, cmp, &options, limit,
)
}
DataType::Utf8 => sort_string::<i32>(values, v, n, &options, limit),
DataType::LargeUtf8 => sort_string::<i64>(values, v, n, &options, limit),
DataType::List(field) => match field.data_type() {
DataType::Int8 => sort_list::<i32, Int8Type>(values, v, n, &options, limit),
DataType::Int16 => sort_list::<i32, Int16Type>(values, v, n, &options, limit),
DataType::Int32 => sort_list::<i32, Int32Type>(values, v, n, &options, limit),
DataType::Int64 => sort_list::<i32, Int64Type>(values, v, n, &options, limit),
DataType::UInt8 => sort_list::<i32, UInt8Type>(values, v, n, &options, limit),
DataType::UInt16 => {
sort_list::<i32, UInt16Type>(values, v, n, &options, limit)
}
DataType::UInt32 => {
sort_list::<i32, UInt32Type>(values, v, n, &options, limit)
}
DataType::UInt64 => {
sort_list::<i32, UInt64Type>(values, v, n, &options, limit)
}
DataType::Float32 => {
sort_list::<i32, Float32Type>(values, v, n, &options, limit)
}
DataType::Float64 => {
sort_list::<i32, Float64Type>(values, v, n, &options, limit)
}
t => {
return Err(ArrowError::ComputeError(format!(
"Sort not supported for list type {:?}",
t
)))
}
},
DataType::LargeList(field) => match field.data_type() {
DataType::Int8 => sort_list::<i64, Int8Type>(values, v, n, &options, limit),
DataType::Int16 => sort_list::<i64, Int16Type>(values, v, n, &options, limit),
DataType::Int32 => sort_list::<i64, Int32Type>(values, v, n, &options, limit),
DataType::Int64 => sort_list::<i64, Int64Type>(values, v, n, &options, limit),
DataType::UInt8 => sort_list::<i64, UInt8Type>(values, v, n, &options, limit),
DataType::UInt16 => {
sort_list::<i64, UInt16Type>(values, v, n, &options, limit)
}
DataType::UInt32 => {
sort_list::<i64, UInt32Type>(values, v, n, &options, limit)
}
DataType::UInt64 => {
sort_list::<i64, UInt64Type>(values, v, n, &options, limit)
}
DataType::Float32 => {
sort_list::<i64, Float32Type>(values, v, n, &options, limit)
}
DataType::Float64 => {
sort_list::<i64, Float64Type>(values, v, n, &options, limit)
}
t => {
return Err(ArrowError::ComputeError(format!(
"Sort not supported for list type {:?}",
t
)))
}
},
DataType::FixedSizeList(field, _) => match field.data_type() {
DataType::Int8 => sort_list::<i32, Int8Type>(values, v, n, &options, limit),
DataType::Int16 => sort_list::<i32, Int16Type>(values, v, n, &options, limit),
DataType::Int32 => sort_list::<i32, Int32Type>(values, v, n, &options, limit),
DataType::Int64 => sort_list::<i32, Int64Type>(values, v, n, &options, limit),
DataType::UInt8 => sort_list::<i32, UInt8Type>(values, v, n, &options, limit),
DataType::UInt16 => {
sort_list::<i32, UInt16Type>(values, v, n, &options, limit)
}
DataType::UInt32 => {
sort_list::<i32, UInt32Type>(values, v, n, &options, limit)
}
DataType::UInt64 => {
sort_list::<i32, UInt64Type>(values, v, n, &options, limit)
}
DataType::Float32 => {
sort_list::<i32, Float32Type>(values, v, n, &options, limit)
}
DataType::Float64 => {
sort_list::<i32, Float64Type>(values, v, n, &options, limit)
}
t => {
return Err(ArrowError::ComputeError(format!(
"Sort not supported for list type {:?}",
t
)))
}
},
DataType::Dictionary(key_type, value_type)
if *value_type.as_ref() == DataType::Utf8 =>
{
match key_type.as_ref() {
DataType::Int8 => {
sort_string_dictionary::<Int8Type>(values, v, n, &options, limit)
}
DataType::Int16 => {
sort_string_dictionary::<Int16Type>(values, v, n, &options, limit)
}
DataType::Int32 => {
sort_string_dictionary::<Int32Type>(values, v, n, &options, limit)
}
DataType::Int64 => {
sort_string_dictionary::<Int64Type>(values, v, n, &options, limit)
}
DataType::UInt8 => {
sort_string_dictionary::<UInt8Type>(values, v, n, &options, limit)
}
DataType::UInt16 => {
sort_string_dictionary::<UInt16Type>(values, v, n, &options, limit)
}
DataType::UInt32 => {
sort_string_dictionary::<UInt32Type>(values, v, n, &options, limit)
}
DataType::UInt64 => {
sort_string_dictionary::<UInt64Type>(values, v, n, &options, limit)
}
t => {
return Err(ArrowError::ComputeError(format!(
"Sort not supported for dictionary key type {:?}",
t
)))
}
}
}
DataType::Binary | DataType::FixedSizeBinary(_) => {
sort_binary::<i32>(values, v, n, &options, limit)
}
DataType::LargeBinary => sort_binary::<i64>(values, v, n, &options, limit),
t => {
return Err(ArrowError::ComputeError(format!(
"Sort not supported for data type {:?}",
t
)))
}
})
}
/// Options that define how sort kernels should behave
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct SortOptions {
/// Whether to sort in descending order
pub descending: bool,
/// Whether to sort nulls first
pub nulls_first: bool,
}
impl Default for SortOptions {
fn default() -> Self {
Self {
descending: false,
// default to nulls first to match spark's behavior
nulls_first: true,
}
}
}
/// Sort boolean values
///
/// when a limit is present, the sort is pair-comparison based as k-select might be more efficient,
/// when the limit is absent, binary partition is used to speed up (which is linear).
///
/// TODO maybe partition_validity call can be eliminated in this case and tri-color sort can be used
/// instead. https://en.wikipedia.org/wiki/Dutch_national_flag_problem
fn sort_boolean(
values: &ArrayRef,
value_indices: Vec<u32>,
mut null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array {
let values = values
.as_any()
.downcast_ref::<BooleanArray>()
.expect("Unable to downcast to boolean array");
let descending = options.descending;
let valids_len = value_indices.len();
let nulls_len = null_indices.len();
let mut len = values.len();
let valids = if let Some(limit) = limit {
len = limit.min(len);
// create tuples that are used for sorting
let mut valids = value_indices
.into_iter()
.map(|index| (index, values.value(index as usize)))
.collect::<Vec<(u32, bool)>>();
sort_valids(descending, &mut valids, &mut null_indices, len, cmp);
valids
} else {
// when limit is not present, we have a better way than sorting: we can just partition
// the vec into [false..., true...] or [true..., false...] when descending
// TODO when https://github.com/rust-lang/rust/issues/62543 is merged we can use partition_in_place
let (mut a, b): (Vec<(u32, bool)>, Vec<(u32, bool)>) = value_indices
.into_iter()
.map(|index| (index, values.value(index as usize)))
.partition(|(_, value)| *value == descending);
a.extend(b);
if descending {
null_indices.reverse();
}
a
};
let nulls = null_indices;
// collect results directly into a buffer instead of a vec to avoid another aligned allocation
let result_capacity = len * std::mem::size_of::<u32>();
let mut result = MutableBuffer::new(result_capacity);
// sets len to capacity so we can access the whole buffer as a typed slice
result.resize(result_capacity, 0);
// Safety: the buffer is always treated as `u32` in the code below
let result_slice: &mut [u32] = unsafe { result.typed_data_mut() };
if options.nulls_first {
let size = nulls_len.min(len);
result_slice[0..size].copy_from_slice(&nulls[0..size]);
if nulls_len < len {
insert_valid_values(result_slice, nulls_len, &valids[0..len - size]);
}
} else {
// nulls last
let size = valids.len().min(len);
insert_valid_values(result_slice, 0, &valids[0..size]);
if len > size {
result_slice[valids_len..].copy_from_slice(&nulls[0..(len - valids_len)]);
}
}
let result_data = unsafe {
ArrayData::new_unchecked(
DataType::UInt32,
len,
Some(0),
None,
0,
vec![result.into()],
vec![],
)
};
UInt32Array::from(result_data)
}
/// Sort primitive values
fn sort_primitive<T, F>(
values: &ArrayRef,
value_indices: Vec<u32>,
null_indices: Vec<u32>,
cmp: F,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array
where
T: ArrowPrimitiveType,
T::Native: std::cmp::PartialOrd,
F: Fn(T::Native, T::Native) -> std::cmp::Ordering,
{
// create tuples that are used for sorting
let valids = {
let values = as_primitive_array::<T>(values);
value_indices
.into_iter()
.map(|index| (index, values.value(index as usize)))
.collect::<Vec<(u32, T::Native)>>()
};
sort_primitive_inner(values, null_indices, cmp, options, limit, valids)
}
// sort is instantiated a lot so we only compile this inner version for each native type
fn sort_primitive_inner<T, F>(
values: &ArrayRef,
null_indices: Vec<u32>,
cmp: F,
options: &SortOptions,
limit: Option<usize>,
mut valids: Vec<(u32, T)>,
) -> UInt32Array
where
T: ArrowNativeType,
T: std::cmp::PartialOrd,
F: Fn(T, T) -> std::cmp::Ordering,
{
let mut nulls = null_indices;
let valids_len = valids.len();
let nulls_len = nulls.len();
let mut len = values.len();
if let Some(limit) = limit {
len = limit.min(len);
}
sort_valids(options.descending, &mut valids, &mut nulls, len, cmp);
// collect results directly into a buffer instead of a vec to avoid another aligned allocation
let result_capacity = len * std::mem::size_of::<u32>();
let mut result = MutableBuffer::new(result_capacity);
// sets len to capacity so we can access the whole buffer as a typed slice
result.resize(result_capacity, 0);
// Safety: the buffer is always treated as `u32` in the code below
let result_slice: &mut [u32] = unsafe { result.typed_data_mut() };
if options.nulls_first {
let size = nulls_len.min(len);
result_slice[0..size].copy_from_slice(&nulls[0..size]);
if nulls_len < len {
insert_valid_values(result_slice, nulls_len, &valids[0..len - size]);
}
} else {
// nulls last
let size = valids.len().min(len);
insert_valid_values(result_slice, 0, &valids[0..size]);
if len > size {
result_slice[valids_len..].copy_from_slice(&nulls[0..(len - valids_len)]);
}
}
let result_data = unsafe {
ArrayData::new_unchecked(
DataType::UInt32,
len,
Some(0),
None,
0,
vec![result.into()],
vec![],
)
};
UInt32Array::from(result_data)
}
// insert valid and nan values in the correct order depending on the descending flag
fn insert_valid_values<T>(result_slice: &mut [u32], offset: usize, valids: &[(u32, T)]) {
let valids_len = valids.len();
// helper to append the index part of the valid tuples
let append_valids = move |dst_slice: &mut [u32]| {
debug_assert_eq!(dst_slice.len(), valids_len);
dst_slice
.iter_mut()
.zip(valids.iter())
.for_each(|(dst, src)| *dst = src.0)
};
append_valids(&mut result_slice[offset..offset + valids.len()]);
}
/// Sort strings
fn sort_string<Offset: StringOffsetSizeTrait>(
values: &ArrayRef,
value_indices: Vec<u32>,
null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array {
let values = values
.as_any()
.downcast_ref::<GenericStringArray<Offset>>()
.unwrap();
sort_string_helper(
values,
value_indices,
null_indices,
options,
limit,
|array, idx| array.value(idx as usize),
)
}
/// Sort dictionary encoded strings
fn sort_string_dictionary<T: ArrowDictionaryKeyType>(
values: &ArrayRef,
value_indices: Vec<u32>,
null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array {
let values: &DictionaryArray<T> = as_dictionary_array::<T>(values);
let keys: &PrimitiveArray<T> = values.keys();
let dict = values.values();
let dict: &StringArray = as_string_array(dict);
sort_string_helper(
keys,
value_indices,
null_indices,
options,
limit,
|array: &PrimitiveArray<T>, idx| -> &str {
let key: T::Native = array.value(idx as usize);
dict.value(key.to_usize().unwrap())
},
)
}
/// shared implementation between dictionary encoded and plain string arrays
#[inline]
fn sort_string_helper<'a, A: Array, F>(
values: &'a A,
value_indices: Vec<u32>,
null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
value_fn: F,
) -> UInt32Array
where
F: Fn(&'a A, u32) -> &str,
{
let mut valids = value_indices
.into_iter()
.map(|index| (index, value_fn(values, index)))
.collect::<Vec<(u32, &str)>>();
let mut nulls = null_indices;
let descending = options.descending;
let mut len = values.len();
if let Some(limit) = limit {
len = limit.min(len);
}
sort_valids(descending, &mut valids, &mut nulls, len, cmp);
// collect the order of valid tuplies
let mut valid_indices: Vec<u32> = valids.iter().map(|tuple| tuple.0).collect();
if options.nulls_first {
nulls.append(&mut valid_indices);
nulls.truncate(len);
UInt32Array::from(nulls)
} else {
// no need to sort nulls as they are in the correct order already
valid_indices.append(&mut nulls);
valid_indices.truncate(len);
UInt32Array::from(valid_indices)
}
}
fn sort_list<S, T>(
values: &ArrayRef,
value_indices: Vec<u32>,
null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array
where
S: OffsetSizeTrait,
T: ArrowPrimitiveType,
T::Native: std::cmp::PartialOrd,
{
sort_list_inner::<S>(values, value_indices, null_indices, options, limit)
}
fn sort_list_inner<S>(
values: &ArrayRef,
value_indices: Vec<u32>,
mut null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array
where
S: OffsetSizeTrait,
{
let mut valids: Vec<(u32, ArrayRef)> = values
.as_any()
.downcast_ref::<FixedSizeListArray>()
.map_or_else(
|| {
let values = as_generic_list_array::<S>(values);
value_indices
.iter()
.copied()
.map(|index| (index, values.value(index as usize)))
.collect()
},
|values| {
value_indices
.iter()
.copied()
.map(|index| (index, values.value(index as usize)))
.collect()
},
);
let mut len = values.len();
let descending = options.descending;
if let Some(limit) = limit {
len = limit.min(len);
}
sort_valids_array(descending, &mut valids, &mut null_indices, len);
let mut valid_indices: Vec<u32> = valids.iter().map(|tuple| tuple.0).collect();
if options.nulls_first {
null_indices.append(&mut valid_indices);
null_indices.truncate(len);
UInt32Array::from(null_indices)
} else {
valid_indices.append(&mut null_indices);
valid_indices.truncate(len);
UInt32Array::from(valid_indices)
}
}
fn sort_binary<S>(
values: &ArrayRef,
value_indices: Vec<u32>,
mut null_indices: Vec<u32>,
options: &SortOptions,
limit: Option<usize>,
) -> UInt32Array
where
S: BinaryOffsetSizeTrait,
{
let mut valids: Vec<(u32, &[u8])> = values
.as_any()
.downcast_ref::<FixedSizeBinaryArray>()
.map_or_else(
|| {
let values = as_generic_binary_array::<S>(values);
value_indices
.iter()
.copied()
.map(|index| (index, values.value(index as usize)))
.collect()
},
|values| {
value_indices
.iter()
.copied()
.map(|index| (index, values.value(index as usize)))
.collect()
},
);
let mut len = values.len();
let descending = options.descending;
if let Some(limit) = limit {
len = limit.min(len);
}
sort_valids(descending, &mut valids, &mut null_indices, len, cmp);
let mut valid_indices: Vec<u32> = valids.iter().map(|tuple| tuple.0).collect();
if options.nulls_first {
null_indices.append(&mut valid_indices);
null_indices.truncate(len);
UInt32Array::from(null_indices)
} else {
valid_indices.append(&mut null_indices);
valid_indices.truncate(len);
UInt32Array::from(valid_indices)
}
}
/// Compare two `Array`s based on the ordering defined in [ord](crate::array::ord).
fn cmp_array(a: &dyn Array, b: &dyn Array) -> Ordering {
let cmp_op = build_compare(a, b).unwrap();
let length = a.len().max(b.len());
for i in 0..length {
let result = cmp_op(i, i);
if result != Ordering::Equal {
return result;
}
}
Ordering::Equal
}
/// One column to be used in lexicographical sort
#[derive(Clone, Debug)]
pub struct SortColumn {
pub values: ArrayRef,
pub options: Option<SortOptions>,
}
/// Sort a list of `ArrayRef` using `SortOptions` provided for each array.
///
/// Performs a stable lexicographical sort on values and indices.
///
/// Returns an `ArrowError::ComputeError(String)` if any of the array type is either unsupported by
/// `lexsort_to_indices` or `take`.
///
/// Example:
///
/// ```
/// use std::convert::From;
/// use std::sync::Arc;
/// use arrow::array::{ArrayRef, StringArray, PrimitiveArray, as_primitive_array};
/// use arrow::compute::kernels::sort::{SortColumn, SortOptions, lexsort};
/// use arrow::datatypes::Int64Type;
///
/// let sorted_columns = lexsort(&vec![
/// SortColumn {
/// values: Arc::new(PrimitiveArray::<Int64Type>::from(vec![
/// None,
/// Some(-2),
/// Some(89),
/// Some(-64),
/// Some(101),
/// ])) as ArrayRef,
/// options: None,
/// },
/// SortColumn {
/// values: Arc::new(StringArray::from(vec![
/// Some("hello"),
/// Some("world"),
/// Some(","),
/// Some("foobar"),
/// Some("!"),
/// ])) as ArrayRef,
/// options: Some(SortOptions {
/// descending: true,
/// nulls_first: false,
/// }),
/// },
/// ], None).unwrap();
///
/// assert_eq!(as_primitive_array::<Int64Type>(&sorted_columns[0]).value(1), -64);
/// assert!(sorted_columns[0].is_null(0));
/// ```
pub fn lexsort(columns: &[SortColumn], limit: Option<usize>) -> Result<Vec<ArrayRef>> {
let indices = lexsort_to_indices(columns, limit)?;
columns
.iter()
.map(|c| take(c.values.as_ref(), &indices, None))
.collect()
}
/// Sort elements lexicographically from a list of `ArrayRef` into an unsigned integer
/// (`UInt32Array`) of indices.
pub fn lexsort_to_indices(
columns: &[SortColumn],
limit: Option<usize>,
) -> Result<UInt32Array> {
if columns.is_empty() {
return Err(ArrowError::InvalidArgumentError(
"Sort requires at least one column".to_string(),
));
}
if columns.len() == 1 {
// fallback to non-lexical sort
let column = &columns[0];
return sort_to_indices(&column.values, column.options, limit);
}
let row_count = columns[0].values.len();
if columns.iter().any(|item| item.values.len() != row_count) {
return Err(ArrowError::ComputeError(
"lexical sort columns have different row counts".to_string(),
));
};
let mut value_indices = (0..row_count).collect::<Vec<usize>>();
let mut len = value_indices.len();
if let Some(limit) = limit {
len = limit.min(len);
}
let lexicographical_comparator = LexicographicalComparator::try_new(columns)?;
// uint32 can be sorted unstably
sort_unstable_by(&mut value_indices, len, |a, b| {
lexicographical_comparator.compare(a, b)
});
Ok(UInt32Array::from(
(&value_indices)[0..len]
.iter()
.map(|i| *i as u32)
.collect::<Vec<u32>>(),
))
}
/// It's unstable_sort, may not preserve the order of equal elements
pub fn partial_sort<T, F>(v: &mut [T], limit: usize, mut is_less: F)
where
F: FnMut(&T, &T) -> Ordering,
{
let (before, _mid, _after) = v.select_nth_unstable_by(limit, &mut is_less);
before.sort_unstable_by(is_less);
}
type LexicographicalCompareItem<'a> = (
&'a ArrayData, // data
DynComparator, // comparator
SortOptions, // sort_option
);
/// A lexicographical comparator that wraps given array data (columns) and can lexicographically compare data
/// at given two indices. The lifetime is the same at the data wrapped.
pub(super) struct LexicographicalComparator<'a> {
compare_items: Vec<LexicographicalCompareItem<'a>>,
}
impl LexicographicalComparator<'_> {
/// lexicographically compare values at the wrapped columns with given indices.
pub(super) fn compare<'a, 'b>(
&'a self,
a_idx: &'b usize,
b_idx: &'b usize,
) -> Ordering {
for (data, comparator, sort_option) in &self.compare_items {
match (data.is_valid(*a_idx), data.is_valid(*b_idx)) {
(true, true) => {
match (comparator)(*a_idx, *b_idx) {
// equal, move on to next column
Ordering::Equal => continue,
order => {
if sort_option.descending {
return order.reverse();
} else {
return order;
}
}
}
}
(false, true) => {
return if sort_option.nulls_first {
Ordering::Less
} else {
Ordering::Greater
};
}
(true, false) => {
return if sort_option.nulls_first {
Ordering::Greater
} else {
Ordering::Less
};
}
// equal, move on to next column
(false, false) => continue,
}
}