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Re: Apply function to parts of a list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg86288] Re: Apply function to parts of a list
  • From: Bill Rowe <readnewsciv at sbcglobal.net>
  • Date: Fri, 7 Mar 2008 02:32:25 -0500 (EST)

On 3/6/08 at 2:59 AM, guerom00 at gmail.com (guerom00) wrote:

>Very often, I find myself having datas to plot of this form :

>data={{x1,y1},{x2,y2},{x3,y3}...{xn,yn}}

>So, very conventional : a list of abscissa and ordinate. Now, let's
>say I want to multiply by 2 all my ascissa. Right now, I write :

>MapAt[2*#&,data,Table[{i,1},{i,1,Length[data]}]]

>It's OK but I isn't there another way to achieve this as I find this
>rather "involved" for such a simple thing ?

There are a variety of other methods such as:

data /.{{a_, b_} :> {2 a, b}}

data.{{2, 0}, {0, 1}}

{2 First@#, Last@#} & /@ data
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