[Numpy-discussion] Adding the ability to "clone" a few fields from a data-type

[Travis E. Oliphant]

Hi all,

I'd like to add to NumPy the ability to clone a data-type object so that 
only a view fields are copied over but that it retains the same total size.

This would allow, for example, the ability to "select out a few records" 
from a structured array using

subarr = arr.view(cloned_dtype)

Right now, it is hard to do this because you have to at least add a 
"dummy" field at the end.  A simple method on the dtype class 
(fromfields or something) would be easy to add.

It was thought in the past to do this with indexing

arr['field1', 'field2']

And that would still be possible (and mostly implemented) if this 
feature is added.

Thoughts?

-Travis