[Numpy-discussion] A few comments (MDP conversion)
Nils Wagner
nwagner at iam.uni-stuttgart.de
Thu Jul 13 11:42:24 EDT 2006
Pietro Berkes wrote:
> Dear numpys,
>
> a couple of weeks ago Tiziano and I completed the conversion of our data
> processing library MDP to numpy. We collected a few ideas and
> questions:
>
> - we found the convertcode.py module quite useful to perform a first,
> low-level conversion. We had some problem when 'typecode' was
> used as a keyword argument because the parser only converts
> 'typecode=' to 'dtype=' and skips the cases where there is an
> additional space character before the equal sign ('typecode =').
> Other names that might be easily converted are 'ArrayType' and
> 'NewAxis'.
>
> - some functions changed the columns/rows conventions ('cov', for
> example). It would be really helpful to explicitly write this in the
> list of necessary changes in the documentation. It could be nice
> to have the file 'convertcode.py' to print a warning every time one
> of this functions is used in the code.
>
> - the linalg functions svd, eig, inv, pinv, diag, and possibly
> others perform an upcast, e.g. from 'f' to 'd'. This is apparently
> because the litelapack module only wraps double precision routines.
> Wouldn't it be more consistent to cast the results back to the
> numerical type of the input? Otherwise, the user always has to take
> care of the casting, which makes the use of single precision
> arrays quite cumbersome.
>
> - we found a bug in the 'eig' function in the case the solution
> is complex: in (linalg.py, line 269) 'Complex' should be 'w.dtype'
>
>
Did you file a ticket ?
http://projects.scipy.org/scipy/numpy
It seems to be line 281 instead of 269. I am using latest svn.
BTW, in linalg.py in
def pinv:
there is another Complex with capital C.
Nils
> We wondered whether it would be possible to obtain SVN write access in
> orderto be able to fix this kind of issues by ourselves in the future.
> We could also contribute docstrings for some of the functions.
>
> In general, we found the conversion to numpy quite straightforward
> and would like to thank you all for the great work!
>
> Cheers,
> Pietro Berkes and Tiziano Zito
> http://mdp-toolkit.sourceforge.net/
>
>
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