Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2012

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: take square of the second and third column of a table

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124186] Re: take square of the second and third column of a table
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Thu, 12 Jan 2012 04:18:18 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201112220.RAA22144@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

You can't really operate upon a "table" in Mathematica, as there is no 
such object. You want instead to operate upon elements at prescribed 
positions in sublists of a list. (You may _display_ such a list of lists 
in Table form.)

Here's one quick way, by example:

   tbl = Partition[RandomInteger[{1, 10}, 12], 3];
   tbl /. {x_, y_, z_}:> {x, y^2, z^2}

On 1/11/12 5:20 PM, hanciong awesome wrote:
> Hello, suppose I have a very long table like this:
>
> 1 2 3
> 4 5 6
> 7 8 9
> .......
> 2 3 4
>
> how can I take square of the 2nd and 3rd column? I always do it by
> making a new table. so let's say the above table is A and it has 100
> lines, then I make the new table as the following:
>
> B=Table[{A[[n]][[1]],A[[n]][[2]]^2,A[[n]][[3]]^2},{n,1,100}]
>
> But if the length of the table is unknown, this way is impractical.
> Could anyone suggests better way? thank you
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305



  • Prev by Date: Re: take square of the second and third column of a table
  • Next by Date: Re: take square of the second and third column of a table
  • Previous by thread: Re: take square of the second and third column of a table
  • Next by thread: Re: take square of the second and third column of a table