[Numpy-discussion] Bug or feature?

Konrad Hinsen konrad.hinsen@fastmail....
Mon Aug 22 02:36:15 CDT 2011

Hi everyone,

I just stumbled on a behavior in NumPy for which I can't find an  
explanation in the documentation. I wonder whether this is a bug or an  
undocumented (or badly documented) feature:

import numpy

t = numpy.dtype([("rotation", numpy.float64, (3, 3)),
                  ("translation", numpy.float64, (3,))])

# works
a1 = numpy.array([], dtype=t)

# doesn't work
a2 = numpy.array((), dtype=t)
# -> ValueError: size of tuple must match number of fields.

According to my understanding of how numpy.array should work, it  
shouldn't make a difference if the first argument is a list or a  
tuple, but in this case there is a difference.


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