Author pitrou
Recipients pitrou, skrah
Date 2019-01-28.20:51:37
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Message-id <1548708697.36.0.695790780311.issue35845@roundup.psfhosted.org>
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This request is motivated in detail here:
https://github.com/python/peps/pull/883#issuecomment-458290745

In short: in C, when you have a Py_buffer, you can directly read the memory in whatever order you want (including physical order).  It is not possible in pure Python, though.  Somewhat unintuitively, memoryview.tobytes() as well as bytes(memoryview) read bytes in *logical* order, even though it flattens the dimensions and doesn't keep the original type.  Logical order is different from physical order for Fortran-contiguous arrays.

One possible way of alleviating this would be to offer a memoryview.transpose() method, similar to the Numpy transpose() method (see https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.transpose.html).

One could also imagine a memoryview.to_c_contiguous() method.

Or even: a memoryview.raw_memory() method, that would 1) flatten dimensions 2) cast to 'B' format 3) keep physical order.
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Date User Action Args
2019-01-28 20:51:40pitrousetrecipients: + pitrou, skrah
2019-01-28 20:51:37pitrousetmessageid: <1548708697.36.0.695790780311.issue35845@roundup.psfhosted.org>
2019-01-28 20:51:37pitroulinkissue35845 messages
2019-01-28 20:51:37pitroucreate