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Re: partition of 2D arrray

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49178] Re: partition of 2D arrray
  • From: Bill Rowe <readnewsciv at earthlink.net>
  • Date: Tue, 6 Jul 2004 03:33:58 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On 7/5/04 at 4:54 AM, ravi at crest.ernet.in (Ravinder Kumar B.) wrote:

>Dear Friends, I have a list of 2D data of the following form:
>{{1,2,3,4},{5,6,7,8},{9,10,11,12},{13,14,15,16}}; In MatrixForm it
>is 4x4 matrix. How do I extract the fisrt two column of the data
>from the above matrix. i.e., {{1,2},{5,6},{9,10},{13,14}}

In[1]:=
a = {{1, 2, 3, 4}, {5, 6, 7, 
     8}, {9, 10, 11, 12}, 
    {13, 14, 15, 16}}; 
    
In[2]:=
a[[All,{1, 2}]]

Out[2]=
{{1, 2}, {5, 6}, {9, 10}, {13, 14}}

In[3]:=
(Take[#1, 2] & ) /@ a

Out[3]=
{{1, 2}, {5, 6}, {9, 10}, {13, 14}}

And there are other ways using the functions in the package Statistics`DataManipulation` or the functions in the package LinearAlgebra`MatrixManipulation`
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