# average or sum, weighted or unweighted, over axes

## Summary
Compute (default weighted) mean of the BaseData signal over the given axes, with proper uncertainty propagation.

## Metadata
- **Module ID:** ReduceDimensionality
- **Module path:** /home/runner/work/MoDaCor/MoDaCor/src/modacor/modules/base_modules/reduce_dimensionality.py
- **Module version:** 20251116.1
- **Keywords:** average, mean, weighted, nanmean, reduce, axis, sum

## Required data keys
- signal

## Modifies
- **signal**: signal, uncertainties, units, weights

## Required arguments
- _None_

## Default configuration
```json
{
  "axes": null,
  "nan_policy": "omit",
  "reduction": "mean",
  "use_weights": true
}
```

## Argument specification
| Argument | Type | Required | Default | Description |
|---|---|---|---|---|
| `axes` | int or list or tuple or NoneType | No | - | Axis or axes to reduce (int, list/tuple, or None for all). |
| `nan_policy` | str | No | omit | NaN handling policy: 'omit' or 'propagate'. |
| `reduction` | str | No | mean | Reduction method: 'mean' or 'sum'. |
| `use_weights` | bool | No | True | Use BaseData weights for weighted reduction. |

## References
DOI 10.1088/0953-8984/25/38/383201

## Notes
This step reduces the dimensionality of the signal by averaging over one or more axes. Units are preserved; axes metadata is currently not adjusted and is left empty on the result.