sparse-llm 0.0.2

Delta compression for LLM fine-tunes - lossless or LoRA-equivalent SVD compression

∴ Sparse

Delta Compression for Fine-tuned Models and Datasets

Compress your 14GB fine-tune to 1.4GB (lossless) or 50MB (LoRA-equivalent). Reconstruct in 4 seconds.

Verified: GPT-2 compression → reconstruction → identical inference output ✅

Quick Start • How It Works • CLI • Python API

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What Sparse Does

Sparse compresses fine-tuned models and derivative datasets as deltas from their base versions.

📦 Model Delta Compression

Mode	Size (7B)	Quality	Use Case
Lossless	~1.4 GB	100%	When quality matters
SVD (LoRA-equiv)	~50 MB	~95-99%	When size matters

Reconstruction: 4 seconds • Works on ANY existing fine-tune

Use cases:

• Compress your existing full fine-tunes (trained without LoRA)
• Share smaller files with collaborators
• Save disk space storing multiple fine-tunes
• Works with ANY training method: full fine-tune, RLHF, merges

📊 Dataset Delta Compression

Metric	Value
Savings	60-80% typical
Use case	Derivative datasets (translations, versions, augmentations)

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Quick Start

pip install sparse-llm

Compress a Fine-tune

# Lossless compression (~1.4GB for 7B model)
sparse compress meta-llama/Llama-2-7b-hf ./my-finetune -o ./my-delta

# OR: Lossy compression (~50MB, LoRA-equivalent quality)
sparse compress-lossy meta-llama/Llama-2-7b-hf ./my-finetune -o ./my-delta --rank 16

Reconstruct from Delta

# From lossless delta
sparse reconstruct meta-llama/Llama-2-7b-hf ./my-delta -o ./reconstructed-model

# From lossy delta
sparse reconstruct-lossy meta-llama/Llama-2-7b-hf ./my-delta -o ./reconstructed-model

Dataset Delta

# Compress derivative dataset
sparse dataset-compress squad squad_v2 -o ./squad_v2_delta

# Reconstruct
sparse dataset-reconstruct ./squad_v2_delta

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How It Works

Fine-tuned Model (14GB)  -  Base Model (14GB)  =  Delta
                                    ↓
                    Lossless: 1.4GB  |  SVD: 50MB
                                    ↓
                         Reconstruct: Base + Delta

Two compression modes:

Mode	How It Works	Size	Quality
Lossless	Sparse + INT8 encoding	~10% of original	100%
SVD	Low-rank approximation (like LoRA)	~0.4% of original	~95-99%

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CLI Reference

# Lossless compression (100% quality)
sparse compress <base> <finetune> -o <output>
sparse reconstruct <base> <delta> [-o <output>]

# Lossy compression (~50MB, LoRA-equivalent quality)
sparse compress-lossy <base> <finetune> -o <output> [--rank 16]
sparse reconstruct-lossy <base> <delta> [-o <output>]

# Adapter packaging
sparse compress-adapter <base> <adapter> -o <output>

# Dataset commands
sparse dataset-compress <base> <derivative> -o <output>
sparse dataset-reconstruct <delta_dir>
sparse dataset-estimate <base> <derivative>

# Info
sparse info <path>

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Python API

from core import compress_delta, reconstruct_from_delta
from core import compress_delta_svd_full, reconstruct_from_svd_delta

# Lossless compression
manifest = compress_delta(
    base_model_id="meta-llama/Llama-2-7b-hf",
    finetune_model_id="./my-finetune",
    output_path="./my-delta"
)
print(f"Compression: {manifest.compression_ratio:.1f}x")  # ~10x

# Extract LoRA (lossy, LoRA-equivalent)
manifest = compress_delta_svd_full(
    base_model_id="meta-llama/Llama-2-7b-hf",
    finetune_model_id="./my-finetune",
    output_path="./my-svd-delta",
    rank=16  # Like LoRA rank
)
print(f"Compression: {manifest.compression_ratio:.1f}x")  # ~280x

# Reconstruct (lossless)
model = reconstruct_from_delta("meta-llama/Llama-2-7b-hf", "./my-delta")

# Reconstruct from extracted LoRA
model = reconstruct_from_svd_delta("meta-llama/Llama-2-7b-hf", "./my-lora-delta")

Dataset API

from core import compress_dataset_delta, reconstruct_from_dataset_delta

# Compress
manifest = compress_dataset_delta("squad", "squad_v2", "./squad_v2_delta")
print(f"Savings: {manifest['size_stats']['savings_pct']:.1f}%")

# Reconstruct
dataset = reconstruct_from_dataset_delta("./squad_v2_delta")

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Why Sparse?

Post-hoc compression for ANY fine-tune. Unlike LoRA (which requires training differently), Sparse works on models you've already trained.

	LoRA/PEFT	Sparse Lossless	Sparse Lossy
When	During training	After training	After training
Size	~50 MB	~1.4 GB	~50 MB
Quality	~95-99%	100%	~95-99%
Works on existing models	❌ No	✅ Yes	✅ Yes

Key insight: Sparse compress-lossy gives you LoRA-sized files from models that weren't trained with LoRA.

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Requirements

• Python 3.9+
• PyTorch 2.0+
• transformers
• Rust (required, included in package)

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Auto-Caching & Fast Reconstruction (If integrated directly into HuggingFace)

Note: This feature is available in the codebase but requires HuggingFace Hub integration to be fully functional.

from core.fast_reconstruct import DeltaCache, from_pretrained_with_delta

# Create cache (reconstructed models stored in ~/.cache/sparse)
cache = DeltaCache()

# Reconstruct and cache - only takes time once!
model_path = cache.get_or_reconstruct(
    base_model_id="meta-llama/Llama-2-7b-hf",
    delta_path="./my-delta",
    background=False  # Wait for completion
)

# Load model from cache
from transformers import AutoModelForCausalLM
model = AutoModelForCausalLM.from_pretrained(model_path)

# Or use drop-in replacement for from_pretrained
model = from_pretrained_with_delta(
    "./my-delta",
    base_model_id="meta-llama/Llama-2-7b-hf"
)

# Prefetch multiple deltas in background (10x faster workflow!)
cache.prefetch_deltas(
    base_model_id="meta-llama/Llama-2-7b-hf",
    delta_paths=["./delta1", "./delta2", "./delta3"]
)

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License

Apache 2.0 - See LICENSE for details.

Free for personal and commercial use.