sample_data/README.md

# Sample Data

A small subset of the [Multisite PPG Dataset](../README.md) for quick inspection, tutorial work, and pipeline testing without pulling the full ~18.6 GB.

## Contents

This subset contains two participants — **P7** and **P8** — laid out exactly like the main dataset:

```
sample_data/
├── raw_data/
│   ├── P7/        # Earring / Necklace / Ring / Watch raw recordings
│   │              # + Polar H10 ECG + Polar H10 accelerometer
│   │              # + activity log
│   └── P8/        # Same structure as P7
└── ppg_windowed_data/
    ├── P7/        # Pre-windowed PPG segments (8 s windows, 1 s stride)
    └── P8/        # Same structure as P7
```

**Total size:** ~1.42 GB.

## How it was obtained

The files in this folder are bit-for-bit copies of `raw_data/P7/`, `raw_data/P8/`, `ppg_windowed_data/P7/`, and `ppg_windowed_data/P8/` from the main dataset — no resampling, filtering, downsampling, or other modification was applied. File schemas, dtypes, sampling rates, units, and gap-handling conventions are identical to the full dataset.

P7 and P8 were chosen as representative samples because both participants have:
- Data from all four wearable sites (Earring, Necklace, Ring, Watch),
- Both Polar H10 reference signals (ECG and 3-axis accelerometer),
- Non-empty self-reported activity logs spanning multiple labelled activities.

## Download just the sample data

If you only want to try the format on a small footprint, fetch this folder alone instead of the whole repository:

```bash
python -c '
from huggingface_hub import snapshot_download
snapshot_download(
    repo_id="anonymous-ppg-dataset/multisite-ppg-submission",
    repo_type="dataset",
    local_dir="anonymous-ppg-dataset/multisite-ppg-submission",
    allow_patterns="sample_data/*",
)
'
```

This pulls roughly 1.42 GB instead of 18.6 GB. Files land under `anonymous-ppg-dataset/multisite-ppg-submission/sample_data/`, mirroring the on-Hub structure.

## Further documentation

For file-level schemas (keys, shapes, dtypes), sampling-rate details, activity-log format, intended uses, limitations, ethics, and license, see the [main dataset README](../README.md). Everything documented there applies identically to this subset.