[Numpy-discussion] Adding a flag to allow integer array access and masking
Travis Oliphant
oliphant.travis at ieee.org
Tue Mar 5 20:44:14 CST 2002
I have not heard any feedback back on my proposal to add a final object to
the extended slice syntax to current Numeric to allow for unambiguous index
and mask-array access.
As a modification to the proposal, suppose we just check to see if the last
argument (of at least two) is a 0d array of type signed byte (currently this
is illegal and will raise an error). This number would be a flag indicating
how to interpret the previous objects. Of course these numbers would be
hidden from the user who would write:
a[index_array, _I] = <values>
b = a[index_array, _I]
or
a[mask_array, _M] = <values>
b = a[mask_array, _M]
where _M is a 0d signed byte array indicating that the mask_array should be
interpreted as a mask while _I is a 0d signed byte array indicating that the
index_array should be interpreted as a integers into the flattened version of
a.
Other indexing schemes could be envisioned as well
a[a1,a2,a3,_X] could be the cross product of the integer arrays a1, a2, and
a3 for example.
or
a[a1, a2, a3, _Z] could select elements from a by "zipping" the sequences a1,
a2, and a3 together to form a list of tuples to grab from a.
Comments?
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