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MathGroup Archive 2003

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Re: proper way to manipulate lists?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg40225] Re: proper way to manipulate lists?
  • From: Bill Rowe <listuser at earthlink.net>
  • Date: Wed, 26 Mar 2003 02:44:10 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

On 3/25/03 at 3:04 AM, nmoore at physics.umn.edu (Nathan Moore) wrote:


>I'm sure this is a one-liner, but it has stumped me for years. 
>Suppose I'm working with a 2-d array of data, data =
>{{x1,y1},{x2,y2}...{xN,yN}}; and I want to transform the data
>according to, data2 = {{x1*a,y1*b},{x2*a,y2*b}...{xN*a,yN*b}}; The
>only way I know to do this is to move the data to excel, performing
>the transform and then move the data back to Mathematica.  This is
>crazy - there must be a better way - is there?  Please tell me there
>is!

Yes, there is. For example

data2 = {a*First[#],b*Last[#]}&/@data will do what you want


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