numpy arrays

Newsgroups	comp.lang.python
Date	2016-03-23 03:06 -0700
Message-ID	<3774dc9b-f9d3-462b-bbe4-41b8b2244db7@googlegroups.com> (permalink)
Subject	numpy arrays
From	Heli <hemla21@gmail.com>

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Hi, 

I have a 2D numpy array like this:

[[1,2,3,4],
 [1,2,3,4], 
 [1,2,3,4]
 [1,2,3,4]]

Is there any fast way to convert this array to 

[[1,1,1,1],
 [2,2,2,2]
 [3,3,3,3]
 [4,4,4,4]]

In general I would need to retrieve every nth element of the interior arrays in to single arrays. I know I can loop over and do this, but I have really big arrays and I need the fastest way to do this. 

Thanks for your help,

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numpy arrays Heli <hemla21@gmail.com> - 2016-03-23 03:06 -0700
  Re: numpy arrays Steven D'Aprano <steve@pearwood.info> - 2016-03-23 21:32 +1100
  Re: numpy arrays Chris Angelico <rosuav@gmail.com> - 2016-03-23 21:35 +1100
    Re: numpy arrays Nobody <nobody@nowhere.invalid> - 2016-03-23 13:45 +0000
      Re: numpy arrays Heli <hemla21@gmail.com> - 2016-04-06 09:26 -0700
        Re: numpy arrays Heli <hemla21@gmail.com> - 2016-04-07 07:31 -0700
          Re: numpy arrays Heli <hemla21@gmail.com> - 2016-04-11 02:17 -0700
          Re: numpy arrays Heli <hemla21@gmail.com> - 2016-04-11 02:32 -0700
  Re: numpy arrays Manolo Martínez <manolo@austrohungaro.com> - 2016-03-23 11:26 +0100
  Re: numpy arrays Heli <hemla21@gmail.com> - 2016-03-23 03:47 -0700
  Re: numpy arrays Simon Ward <simon+python@bleah.co.uk> - 2016-03-23 10:47 +0000

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