Re: partition of 2D arrray
- To: mathgroup at smc.vnet.net
- Subject: [mg49161] Re: partition of 2D arrray
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 6 Jul 2004 03:33:18 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <ccb54i$ei1$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
lst = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};
lst[[All, {1, 2}]]
Take[#, 2] & /@ lst
Drop[#,-2] & /@ lst
Transpose[Take[Transpose[lst], 2]]
SetAttributes[If, SequenceHold]
MapIndexed[If[Last[#2] <= 2, #1, Sequence[]] &, lst, {2}]
Regards
Jens
"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}}
>
> --
> Regards, Jul 2
> Ravi
>
> |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
> | Ravinder Kumar Banyal (SRF), |
> | Indian Institute of Astrophysics, |
> | Koramangala Bangalore - 560 034. INDIA |
> | email : banyal at iiap.res.in, ravi at crest.ernet.in |
> | Ph No : 080 25530672 (IIA) 080 7931972 (Hoskote)|
> | 7931952 |
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Philosophers have interpreted the world in various ways, but the point is
> to change it. --Karl Marx