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use std::ops::Add;
use crate::array::{Array, PrimitiveArray};
use crate::datatypes::ArrowNumericType;
pub fn min<T>(array: &PrimitiveArray<T>) -> Option<T::Native>
where
T: ArrowNumericType,
{
min_max_helper(array, |a, b| a < b)
}
pub fn max<T>(array: &PrimitiveArray<T>) -> Option<T::Native>
where
T: ArrowNumericType,
{
min_max_helper(array, |a, b| a > b)
}
fn min_max_helper<T, F>(array: &PrimitiveArray<T>, cmp: F) -> Option<T::Native>
where
T: ArrowNumericType,
F: Fn(T::Native, T::Native) -> bool,
{
let mut n: Option<T::Native> = None;
let data = array.data();
for i in 0..data.len() {
if data.is_null(i) {
continue;
}
let m = array.value(i);
match n {
None => n = Some(m),
Some(nn) => {
if cmp(m, nn) {
n = Some(m)
}
}
}
}
n
}
pub fn sum<T>(array: &PrimitiveArray<T>) -> Option<T::Native>
where
T: ArrowNumericType,
T::Native: Add<Output = T::Native>,
{
let null_count = array.null_count();
if null_count == array.len() {
None
} else if null_count == 0 {
let mut n: T::Native = T::default_value();
let data = array.data();
let m = array.value_slice(0, data.len());
for item in m.iter().take(data.len()) {
n = n + *item;
}
Some(n)
} else {
let mut n: T::Native = T::default_value();
let data = array.data();
let m = array.value_slice(0, data.len());
for (i, item) in m.iter().enumerate() {
if data.is_valid(i) {
n = n + *item;
}
}
Some(n)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::array::*;
#[test]
fn test_primitive_array_sum() {
let a = Int32Array::from(vec![1, 2, 3, 4, 5]);
assert_eq!(15, sum(&a).unwrap());
}
#[test]
fn test_primitive_array_float_sum() {
let a = Float64Array::from(vec![1.1, 2.2, 3.3, 4.4, 5.5]);
assert_eq!(16.5, sum(&a).unwrap());
}
#[test]
fn test_primitive_array_sum_with_nulls() {
let a = Int32Array::from(vec![None, Some(2), Some(3), None, Some(5)]);
assert_eq!(10, sum(&a).unwrap());
}
#[test]
fn test_primitive_array_sum_all_nulls() {
let a = Int32Array::from(vec![None, None, None]);
assert_eq!(None, sum(&a));
}
#[test]
fn test_buffer_array_min_max() {
let a = Int32Array::from(vec![5, 6, 7, 8, 9]);
assert_eq!(5, min(&a).unwrap());
assert_eq!(9, max(&a).unwrap());
}
#[test]
fn test_buffer_array_min_max_with_nulls() {
let a = Int32Array::from(vec![Some(5), None, None, Some(8), Some(9)]);
assert_eq!(5, min(&a).unwrap());
assert_eq!(9, max(&a).unwrap());
}
}