All, I just posted on the DeveloperZone of the wiki the latest version of maskedarray, an alternative to numpy.core.ma. You can download it here: http://projects.scipy.org/scipy/numpy/attachment/wiki/MaskedArray/maskedarra... The package has three modules: core (with the basic functions of numpy.core.ma), extras (which adds some functions, such as apply_along_axis, or the concatenator mr_), and testutils (which adds support for maskedarray for the tests functions). It also comes with its test suite (available in the tests subdirectory). For those of you who were not aware of it, the new MaskedArray is a subclass of ndarray, and it accepts any subclass of ndarray as data. You can use it as you would with numpy.core.ma.MaskedArray. For those of you who already tested the package, the main modifications are: - the reorganization of the initial module in core+extras. - Data are now shared by default (in other terms, the copy flag defaults to False in MaskedArray.__new__), for consistency with the rest of numpy. - An additional boolean flag has been introduced: keep_mask (with a default of True). This flag is useful when trying to mask a mask array: it tells __new__ whether to keep the initial mask (in that case, the new mask will be combined with the old mask) or not (in that case, the new mask replaces the old one). - Some functions/routines that were missing have been added (any/all...) As always, this is a work in progress. In particular, I should really check for the bottlenecks: would anybody have some pointers ? If you wanna be on the safe, optimized side, stick to numpy.core.ma. Otherwise, please try this new implementation, and don't forget to give me some feedback! PS: Technical question: how can I delete some files in the DeveloperZone wiki ? The maskedarray.py, test_maskedarray.py, test_subclasses.py are out of date, and should be replaced by the package. Thanks a lot in advance !