On Wed, Oct 20, 2010 at 5:08 PM, Matthew Brett <matthew.brett@gmail.com> wrote:

Hi,

I have just run into this oddness:

In [28]: dt1 = np.dtype('f4')

In [29]: dt1.str Out[29]: '<f4'

In [30]: dt2 = dt1.newbyteorder('<')

In [31]: dt2.str Out[31]: '<f4'

In [32]: dt1 == dt2 Out[32]: True

In [33]: hash(dt1) == hash(dt2) Out[33]: False

This is the same as:

http://www.mail-archive.com/numpy-discussion@scipy.org/msg13299.html

My question was - does the team still agree this is a bug?

This should have been fixed when I implemented the hashing protocol for dtypes. This is a bug in the hashing protocol implementation, most likely caused by "=" and "<" being considered different by the hashing function. I will try to take a look at it (the function to fix is _array_descr_builtin in hashdesc.c if you feel like doing some C right now :) ). cheers, David