[Numpy-discussion] Extracting sub-fields from an array as a view (PR 350)

Travis Oliphant travis@continuum...
Sat Jul 14 17:31:35 CDT 2012


In  https://github.com/numpy/numpy/pull/350/files , 

javius provides a patch to allow field extraction from a structured array to return a view instead of a copy.    Generally, this is consistent with the desire to have NumPy return views whenever it can.   The same idea underlies the change to the diagonal method. 

Suppose 'myarr' is a structured array with fields ['lat', 'long', 'meas1', 'meas2', 'meas3', 'meas4']. 

Currently, 

myarr[['lat', 'long', 'mesa3']] will return a copy of the data in the underlying array.   The proposal is to have this return a view, but do it in a two-stage approach so that a first version returns a copy with the WARN_ON_WRITE flag set introduced in NumPy 1.7.   A later version will remove the flag (and the copy). 

What are thoughts on this proposal and which version of NumPy it should go in?

-Travis
 
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