       Re: proper way to manipulate lists?

• To: mathgroup at smc.vnet.net
• Subject: [mg40185] Re: proper way to manipulate lists?
• From: burd at gmx.net (Oleg)
• Date: Tue, 25 Mar 2003 14:47:23 -0500 (EST)
• References: <b5p158\$7sk\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```One of the possible solutions:

array = Table[{"x" <> ToString[i], "y" <> ToString[i]}, {i, 10^4}] //
ToExpression;

In:=
ByteCount[array]

Out=
280024

In:=
array[]

Out=
{x100, y100}

In:=
array2 = {a #[], b #[]} & /@ array; // Timing

Out=
{0.094 Second, Null}

In:=
array2[]

Out=
{a x100, b y100}

Nathan Moore <nmoore at physics.umn.edu> wrote in message news:<b5p158\$7sk\$1 at smc.vnet.net>...
> 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!
>
> regards,
>
> Nathan Moore, University of Minnesota Physics Department

```

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