[AstroPy] Problem with astropy 03 and quantities

Yannick Roehlly yannick.roehlly at lam.fr
Sun Nov 24 18:50:23 EST 2013

Dear all,

I've encountered a problem with astropy 0.3 and I wonder how to solve
it and if it's an astropy issue or not.

I've got some code (a SED fitting code) that used to work with astropy
0.2.5 and no longer works with version 0.3, failing with a "ValueError:
setting an array element with a sequence." when trying to copy an array
with numpy.copy.

I managed to trace the problem. At some point, I'm using the cosmology
module to compute a luminosity distance while building an array of
fluxes. With astropy 0.3, the luminosity_distance functions returns
quantities. So I have a "quantified" array that can not be copied with

So, I wonder if there is a way to disable this behaviour and make
astropy not use quantities.

Also, I wonder if this is not an astropy issue as it breaks working
code (at least, there should be a warning in the changelog).


PS: Does the use of quantities slows down the computation or their
effect is negligible?

Wernher von Braun settled for a V-2 when he coulda had a V-8.

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