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RE: Question on Ordering

• To: mathgroup at smc.vnet.net
• Subject: [mg47050] RE: [mg47007] Question on Ordering
• From: "Owen, HL (Hywel)" <H.L.Owen at dl.ac.uk>
• Date: Mon, 22 Mar 2004 05:19:17 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi David,

Thanks for that. However, this only works in general for Hue, and not for,
say, GrayLevel, or other color functions that take 0-1 arguments (like the
really handy GradientColor function posted in the past). I can't see how to
insert

Normalise[list_]:=((list-#)/(Max[list]-#))&[Min[list]]

into this to fix it though. Thanks for the tip on Inner though.

Hywel

> -----Original Message-----
> From: David Park [mailto:djmp at earthlink.net]
To: mathgroup at smc.vnet.net
> Sent: 20 March 2004 15:18
> To: Owen, HL (Hywel); mathgroup at smc.vnet.net
> Subject: [mg47050] RE: [mg47007] Question on Ordering
> 
> 
> Hywel,
> 
> When one wants to combine two equal length lists to produce a 
> new list in
> the same order, the command to use is Inner. Here is an 
> example for your
> type of plot.
> 
> alist = Table[Sin[2\[Pi] x], {x, 0, 1, 0.05}];
> blist = Table[x, {x, 0, 1, 0.05}];
> 
> plotdata = Inner[{Hue[#2], Point[{#2, #1}]} &, alist, blist, List];
> 
> Needs["Graphics`Colors`"]
> Show[Graphics[{AbsolutePointSize[4], plotdata}],
>     Frame -> True,
>     PlotLabel -> "Rendering Controlled by x Value",
>     ImageSize -> 450,
>     Background -> Linen];
> 
> Just for fun, here is another unconventional use of Inner: 
> dividing one
> equation by another.
> 
> eqn1 = a x == b;
> eqn2 = c y == d;
> 
> Inner[Divide, eqn1, eqn2, Equal]
> (a*x)/(c*y) == b/d
> 
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/
> 
> 
> 
> From: Owen, HL (Hywel) [mailto:H.L.Owen at dl.ac.uk]
To: mathgroup at smc.vnet.net
> 
> I have two sets of data A and B of the same length, that I'd 
> like to plot
> one against the other - this is easy of course:
> 
> ListPlot[Transpose[{A,B}]
> 
> What I'd like to do next is to colour each point according to 
> the value of B
> (or A in principle). The points are easily generated using:
> 
> Point[#]&/@Transpose[{A,B}]
> 
> And if I have a list of colours C I can do something like
> 
> {Hue[#]&/@C,Point[#]&/@Transpose[{A,B}]}//Transpose//Graphics//Show
> 
> The question is how to generate the list of colours C. Note 
> that I don't
> want to sort A and B, since I want to leave them alone to 
> plot {A,D}, {A,E}
> later on.
> 
> I tried various combinations of Ordering[] and Position[] but 
> didn't get
> anywhere. Anyone have any idea?
> 
> Thanks,
> 
> Hywel
> 
> -------------------------------------------------------------------
> Hywel Owen                                      h.owen'at'dl.ac.uk
> Accelerator Science and Technology Centre
> Daresbury Laboratory, Warrington WA4 4AD, UK
> Tel: +44 1925 603797 Fax: +44 1925 603192
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