README.md

# DLSCA Test Dataset

A Hugging Face dataset for Deep Learning Side Channel Analysis (DLSCA) with streaming support for large trace files using zarr format.

## Features

- **Streaming Support**: Large trace data is converted to zarr format with chunking for efficient streaming access
- **Caching**: Uses Hugging Face cache instead of fsspec cache for better integration
- **Zip Compression**: Zarr chunks are stored in zip files to minimize file count
- **Memory Efficient**: Only loads required chunks, not the entire dataset

## Dataset Structure

- **Labels**: 1000 examples with 4 labels each (int32)
- **Traces**: 1000 examples with 20,971 features each (int8)
- **Index**: Sequential index for each example

## Usage

### Local Development

```python
from test import TestDataset

# Load dataset locally
dataset = TestDataset()
dataset.download_and_prepare()
dataset_dict = dataset.as_dataset(split="train")

# Access examples
example = dataset_dict[0]
print(f"Labels: {example['labels']}")
print(f"Traces length: {len(example['traces'])}")
```

### Streaming Usage (for large datasets)

```python
from test import TestDownloadManager, TestDataset

# Initialize streaming dataset
dl_manager = TestDownloadManager()
traces_path = "data/traces.npy"
zarr_zip_path = dl_manager.download_zarr_chunks(traces_path, chunk_size=100)

# Access zarr data efficiently
dataset = TestDataset()
zarr_array = dataset._load_zarr_from_zip(zarr_zip_path)

# Access specific chunks
chunk_data = zarr_array[0:100]  # First chunk
```

### Chunk Selection

```python
# Select specific ranges for training
selected_range = slice(200, 300)
selected_traces = zarr_array[selected_range]
selected_labels = labels[selected_range]
```

## Implementation Details

### Custom DownloadManager

The `TestDownloadManager` extends `datasets.DownloadManager` to:
- Convert numpy arrays to zarr format with chunking
- Store zarr data in zip files for compression
- Use Hugging Face cache directory
- Support streaming access patterns

### Custom Dataset Builder

The `TestDataset` extends `datasets.GeneratorBasedBuilder` to:
- Handle both local numpy files and remote zarr chunks
- Provide efficient chunk-based data access
- Maintain compatibility with Hugging Face datasets API

### Zarr Configuration

- **Format**: Zarr v2 (for better fsspec compatibility)
- **Chunks**: (100, 20971) - 100 examples per chunk
- **Compression**: ZIP format for the zarr store
- **Storage**: Hugging Face cache directory

## Performance

The zarr-based approach provides:
- **Memory efficiency**: Only loads required chunks
- **Streaming capability**: Can work with datasets larger than RAM
- **Compression**: Zip storage reduces file size
- **Cache optimization**: Leverages Hugging Face caching mechanism

## Requirements

```
datasets
zarr<3
fsspec
numpy
zipfile36
```

## File Structure

```
test/
├── data/
│   ├── labels.npy          # Label data (small, kept as numpy)
│   └── traces.npy          # Trace data (large, converted to zarr)
├── test.py                 # Main dataset implementation
├── example_usage.py        # Usage examples
├── requirements.txt        # Dependencies
└── README.md              # This file
```

## Notes

- The original `traces.npy` is ~20MB, which demonstrates the zarr chunking approach
- For even larger datasets (GB/TB), this approach scales well
- The zarr v2 format is used for better compatibility with fsspec
- Chunk size can be adjusted based on memory constraints and access patterns

## Future Enhancements

- Support for multiple splits (train/test/validation)
- Dynamic chunk size based on available memory
- Compression algorithms for zarr chunks
- Metadata caching for faster dataset initialization