RE: Question on Ordering

• To: mathgroup at smc.vnet.net
• Subject: [mg47030] RE: [mg47007] Question on Ordering
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 22 Mar 2004 05:18:42 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```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

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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