Masked arrays

No files, tests, or entry points are named. Start by reviewing ndarray's current array trait and abstractions, then compare the proposed wrapper and mask cases against those constraints. Done would require a settled implementation direction for masked arrays, rather than an unresolved design discussion.

Numpy supports masked arrays which is very useful for many use-cases. Are there any plans how a similar feature could be implemented for rust-ndarray?

My current idea would be to build a decorator which wraps an array and contains an additional mask object: struct MaskedArray<A, M>{ array: A, mask: M, }

The mask itself should be a trait (and/or enum?) to handle the following cases:

• empty (no elements are masked)
• hard mask: a bool array with the same shape as the data array (masking by coordinate)
• no-data value (masking by value)
• predicate (masking by value and/or coordinate)

The problem with this approach is that there is currently no array trait which is needed for the decorator pattern.