18.1 What is a masked array?

Masked arrays are arrays that may have missing or invalid entries. Module numarray.ma provides a work-alike replacement for numarray that supports data arrays with masks. A mask is either None or an array of ones and zeros, that determines for each element of the masked array whether or not it contains an invalid entry. The package assures that invalid entries are not used in computations. A particular element is said to be masked (invalid) if the mask is not None and the corresponding element of the mask is 1; otherwise it is unmasked (valid).

This package was written by Paul F. Dubois at Lawrence Livermore National Laboratory. Please see the legal notice in the software and section ``License and disclaimer for packages numarray.ma''.

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