deepcopy of Quantity discards units #27

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1. lumbric commented on Aug 27, 2013

   

   lumbric

   on Aug 27, 2013

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   This issue seems to be caused by numpy:
   http://numpy-discussion.10968.n7.nabble.com/array-flags-not-copied-deepcopied-td31860.html

   Note that the copy argument of the Quantity is set to True by default. This argument is inherited from numpy. But this does not resolve the case where you have several nested dictionaries containing quantities and you need to copy it.
2. xubuntix commented on Feb 20, 2014

   

   xubuntix

   on Feb 20, 2014

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   I think this happens, because quantities.Quantity does not define its own deepcopy method, but the one from numpy.ndarray is used (Quantity inherits from ndarray).
   Monkey Patching Quantitiy like this:

       quantities.Quantity.__deepcopy__ = lambda x,y: quantities.Quantity(x.magnitude, x.dimensionality)

   seems to help.
3. lumbric

   added a commit that references this issue on Mar 23, 2014

   add __deepcopy__ method for Quantity, fixes python-quantities#27

   ...

   This issue will close once commit fc0e1ba is merged into the 'master' branch.

   fc0e1ba
4. lumbric commented on Mar 23, 2014

   

   lumbric

   on Mar 23, 2014

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   You are right. Ignore my last comment.

   I added a pull request in #78.
5. ddale

   closed this as completedin fe3effbon Dec 16, 2015