[GitHub] [arrow] jorgecarleitao commented on a change in pull request #9313: [Rust] [Experiment] Trigonometry kernels

[GitBox <gi...@apache.org>]

jorgecarleitao commented on a change in pull request #9313:
URL: https://github.com/apache/arrow/pull/9313#discussion_r564708601



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File path: rust/arrow/src/compute/kernels/trigonometry.rs
##########
@@ -0,0 +1,248 @@
+// 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 trigonometry kernels for `PrimitiveArrays` that are
+//! floats, restricted by the [num::Float] trait.
+
+use std::{iter::FromIterator, ops::Div};
+
+use num::{Float, Zero};
+
+use super::math::*;
+use crate::buffer::Buffer;
+use crate::datatypes::ArrowNumericType;
+use crate::error::Result;
+use crate::{
+    array::*,
+    compute::{add, math_op, multiply, subtract},
+    datatypes::ArrowPrimitiveType,
+    error::ArrowError,
+    float_unary,
+};
+
+use super::unary::{into_primitive_array_data, unary};
+
+float_unary!(to_degrees);
+float_unary!(to_radians);
+float_unary!(sin);
+float_unary!(cos);
+float_unary!(tan);
+float_unary!(asin);
+float_unary!(acos);
+float_unary!(atan);
+float_unary!(sinh);
+float_unary!(cosh);
+float_unary!(tanh);
+float_unary!(asinh);
+float_unary!(acosh);
+float_unary!(atanh);
+
+pub fn atan2<T>(
+    left: &PrimitiveArray<T>,
+    right: &PrimitiveArray<T>,
+) -> Result<PrimitiveArray<T>>
+where
+    T: ArrowNumericType,
+    T::Native: num::traits::Float,
+{
+    math_op(left, right, |x, y| x.atan2(y))
+}
+
+/// Perform `left * right` operation on two arrays. If either left or right value is null
+/// then the result is also null.
+pub fn sin_cos<T>(array: &PrimitiveArray<T>) -> (PrimitiveArray<T>, PrimitiveArray<T>)
+where
+    T: ArrowNumericType,
+    T::Native: num::traits::Float,
+{
+    let (sin, cos): (Vec<T::Native>, Vec<T::Native>) =
+        array.values().iter().map(|v| v.sin_cos()).unzip();
+    // NOTE: due to `unzip` collecting and splitting the arrays,
+    // this might be slower than Buffer::from_trusted_len_iter
+    let sin_buffer = Buffer::from_iter(sin);
+    let cos_buffer = Buffer::from_iter(cos);
+
+    let sin_data = into_primitive_array_data::<_, T>(array, sin_buffer);
+    let cos_data = into_primitive_array_data::<_, T>(array, cos_buffer);
+    (
+        PrimitiveArray::<T>::from(std::sync::Arc::new(sin_data)),
+        PrimitiveArray::<T>::from(std::sync::Arc::new(cos_data)),
+    )
+}
+
+/// Calculate the Haversine distance between two geographic coordinates.
+/// Based on the haversine crate.
+///
+/// The distance returned is in meters, and the radius must be specified in meters.
+pub fn haversine<T>(
+    lat_a: &PrimitiveArray<T>,
+    lng_a: &PrimitiveArray<T>,
+    lat_b: &PrimitiveArray<T>,
+    lng_b: &PrimitiveArray<T>,
+    radius: impl num::traits::Float,
+) -> Result<PrimitiveArray<T>>
+where
+    T: ArrowPrimitiveType + ArrowNumericType,
+    T::Native: num::traits::Float + Div<Output = T::Native> + Zero + num::NumCast,
+{
+    // Check array lengths, must all equal
+    let len = lat_a.len();
+    if lat_b.len() != len || lng_a.len() != len || lng_b.len() != len {
+        return Err(ArrowError::ComputeError(
+            "Cannot perform math operation on arrays of different length".to_string(),
+        ));
+    }
+    // These casts normally get optimized to f64 as f64
+    let one = num::cast::<_, T::Native>(1.0).unwrap();

Review comment:
       I did not find any easy way of doing this, also. It feels like we would need a generic of a generic. It looks good to me, though.




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