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Re: Numpy Array of Sets

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On 2014-05-24 23:05, Luis José Novoa wrote:
> Hi All,
>
> Hope you're doing great. One quick question. I am defining an array of sets using numpy as:
>
> a=array([set([])]*3)
>
> Now, if I want to add an element to the set in, lets say, a[0], and I use the .add(4) operation, which results in:
>
> array([set([4]), set([4]), set([4])], dtype=object)
>
> which I do not want. If I use the union operator
>
> a[0] = a[0] | set([4])
>
> then I obtain what I want:
>
> array([set([4]), set([]), set([])], dtype=object)
>
> Can anyone explain whay this happens?

Same reason why you shouldn't make a list of lists like so: [[]]*3

https://docs.python.org/2/faq/programming.html#how-do-i-create-a-multidimensional-list

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

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Numpy Array of Sets Luis José Novoa <luisjosenovoa@gmail.com> - 2014-05-24 15:05 -0700
  Re: Numpy Array of Sets Robert Kern <robert.kern@gmail.com> - 2014-05-24 23:14 +0100
  Re: Numpy Array of Sets Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2014-05-25 00:25 +0200
    Re: Numpy Array of Sets LJ <luisjosenovoa@gmail.com> - 2014-05-25 05:29 -0700
      Re: Numpy Array of Sets Peter Otten <__peter__@web.de> - 2014-05-25 15:26 +0200
        Re: Numpy Array of Sets LJ <luisjosenovoa@gmail.com> - 2014-05-25 07:14 -0700
          Re: Numpy Array of Sets Peter Otten <__peter__@web.de> - 2014-05-25 17:12 +0200
            Re: Numpy Array of Sets LJ <luisjosenovoa@gmail.com> - 2014-05-25 08:17 -0700

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