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

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124192] Re: take square of the second and third column of a table
  • From: Tomas Garza <tgarza10 at msn.com>
  • Date: Thu, 12 Jan 2012 04:20:22 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201112220.RAA22144@smc.vnet.net>

For example,
b = Table[RandomInteger[{0, 9}], {10}, {3}];(avoid capitalizing your variables to prevent conflicts with Mathematica's own symbols)
One possibility is as follows:
{#[[1]], #[[2]]^2, #[[3]]^2} & /@ b
This is functional programming, where you don't have t worry about table lengths and all that stuff.
-Tomas

> Date: Wed, 11 Jan 2012 17:20:16 -0500
> From: hanciong at gmail.com
> Subject: take square of the second and third column of a table
> To: mathgroup at smc.vnet.net
>
> 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
>


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