vortex-array 0.59.4

Vortex in memory columnar data format
Documentation 
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// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright the Vortex contributors

use itertools::Itertools;
use vortex_dtype::NativePType;
use vortex_dtype::Nullability::NonNullable;
use vortex_dtype::match_each_native_ptype;
use vortex_error::VortexResult;
use vortex_mask::Mask;

use crate::arrays::PrimitiveArray;
use crate::arrays::PrimitiveVTable;
use crate::compute::MinMaxKernel;
use crate::compute::MinMaxKernelAdapter;
use crate::compute::MinMaxResult;
use crate::register_kernel;
use crate::scalar::PValue;
use crate::scalar::Scalar;

impl MinMaxKernel for PrimitiveVTable {
    fn min_max(&self, array: &PrimitiveArray) -> VortexResult<Option<MinMaxResult>> {
        match_each_native_ptype!(array.ptype(), |T| {
            compute_min_max_with_validity::<T>(array)
        })
    }
}

register_kernel!(MinMaxKernelAdapter(PrimitiveVTable).lift());

#[inline]
fn compute_min_max_with_validity<T>(array: &PrimitiveArray) -> VortexResult<Option<MinMaxResult>>
where
    T: NativePType,
    PValue: From<T>,
{
    Ok(match array.validity_mask()? {
        Mask::AllTrue(_) => compute_min_max(array.as_slice::<T>().iter()),
        Mask::AllFalse(_) => None,
        Mask::Values(v) => compute_min_max(
            array
                .as_slice::<T>()
                .iter()
                .zip(v.bit_buffer().iter())
                .filter_map(|(v, m)| m.then_some(v)),
        ),
    })
}

fn compute_min_max<'a, T>(iter: impl Iterator<Item = &'a T>) -> Option<MinMaxResult>
where
    T: NativePType,
    PValue: From<T>,
{
    // `total_compare` function provides a total ordering (even for NaN values).
    // However, we exclude NaNs from min max as they're not useful for any purpose where min/max would be used
    match iter
        .filter(|v| !v.is_nan())
        .minmax_by(|a, b| a.total_compare(**b))
    {
        itertools::MinMaxResult::NoElements => None,
        itertools::MinMaxResult::OneElement(&x) => {
            let scalar = Scalar::primitive(x, NonNullable);
            Some(MinMaxResult {
                min: scalar.clone(),
                max: scalar,
            })
        }
        itertools::MinMaxResult::MinMax(&min, &max) => Some(MinMaxResult {
            min: Scalar::primitive(min, NonNullable),
            max: Scalar::primitive(max, NonNullable),
        }),
    }
}

#[cfg(test)]
mod tests {
    use vortex_buffer::buffer;

    use crate::arrays::PrimitiveArray;
    use crate::compute::min_max;
    use crate::validity::Validity;

    #[test]
    fn min_max_nan() {
        let array = PrimitiveArray::new(
            buffer![f32::NAN, -f32::NAN, -1.0, 1.0],
            Validity::NonNullable,
        );
        let min_max = min_max(array.as_ref()).unwrap().unwrap();
        assert_eq!(f32::try_from(&min_max.min).unwrap(), -1.0);
        assert_eq!(f32::try_from(&min_max.max).unwrap(), 1.0);
    }

    #[test]
    fn min_max_inf() {
        let array = PrimitiveArray::new(
            buffer![f32::INFINITY, f32::NEG_INFINITY, -1.0, 1.0],
            Validity::NonNullable,
        );
        let min_max = min_max(array.as_ref()).unwrap().unwrap();
        assert_eq!(f32::try_from(&min_max.min).unwrap(), f32::NEG_INFINITY);
        assert_eq!(f32::try_from(&min_max.max).unwrap(), f32::INFINITY);
    }
}