Proposed new feature or change:

Currently, numpy.ptp (peak-to-peak: max - min) does not accept the where argument, unlike other reduction functions such as sum, min, max, and mean.

This creates an inconsistency in the API and forces users to pre-mask arrays (e.g., x[mask]) when selectively computing the range of values.

Proposed Enhancement

Extend np.ptp to accept a where parameter, consistent with other reductions. The where mask will be forwarded to both the underlying maximum and minimum reductions.