vortex-btrblocks 0.74.0

BtrBlocks style compressor
Documentation 
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// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright the Vortex contributors

//! ALPRD (ALP with Real Double) encoding variant.

use vortex_alp::ALPRDArrayExt;
use vortex_alp::ALPRDArrayOwnedExt;
use vortex_alp::RDEncoder;
use vortex_array::ArrayRef;
use vortex_array::Canonical;
use vortex_array::ExecutionCtx;
use vortex_array::IntoArray;
use vortex_array::arrays::primitive::PrimitiveArrayExt;
use vortex_array::dtype::PType;
use vortex_compressor::estimate::CompressionEstimate;
use vortex_compressor::estimate::DeferredEstimate;
use vortex_compressor::estimate::EstimateVerdict;
use vortex_error::VortexResult;
use vortex_error::vortex_panic;

use crate::ArrayAndStats;
use crate::CascadingCompressor;
use crate::CompressorContext;
use crate::Scheme;
use crate::compress_patches;

/// ALPRD (ALP with Real Double) encoding variant.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct ALPRDScheme;

impl Scheme for ALPRDScheme {
    fn scheme_name(&self) -> &'static str {
        "vortex.float.alprd"
    }

    fn matches(&self, canonical: &Canonical) -> bool {
        canonical.dtype().is_float()
    }

    fn expected_compression_ratio(
        &self,
        data: &ArrayAndStats,
        _compress_ctx: CompressorContext,
        _exec_ctx: &mut ExecutionCtx,
    ) -> CompressionEstimate {
        // We don't support ALPRD for f16.
        if data.array_as_primitive().ptype() == PType::F16 {
            return CompressionEstimate::Verdict(EstimateVerdict::Skip);
        }

        CompressionEstimate::Deferred(DeferredEstimate::Sample)
    }

    fn compress(
        &self,
        _compressor: &CascadingCompressor,
        data: &ArrayAndStats,
        _compress_ctx: CompressorContext,
        exec_ctx: &mut ExecutionCtx,
    ) -> VortexResult<ArrayRef> {
        let primitive_array = data.array_as_primitive();

        let encoder = match primitive_array.ptype() {
            PType::F32 => RDEncoder::new(primitive_array.as_slice::<f32>()),
            PType::F64 => RDEncoder::new(primitive_array.as_slice::<f64>()),
            ptype => vortex_panic!("cannot ALPRD compress ptype {ptype}"),
        };

        let alp_rd = encoder.encode(primitive_array, exec_ctx);
        let dtype = alp_rd.dtype().clone();
        let right_bit_width = alp_rd.right_bit_width();
        let mut parts = ALPRDArrayOwnedExt::into_data_parts(alp_rd);
        parts.left_parts_patches = parts
            .left_parts_patches
            .map(|p| compress_patches(p, exec_ctx))
            .transpose()?;

        Ok(vortex_alp::ALPRD::try_new(
            dtype,
            parts.left_parts,
            parts.left_parts_dictionary,
            parts.right_parts,
            right_bit_width,
            parts.left_parts_patches,
            exec_ctx,
        )?
        .into_array())
    }
}