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Re: Associate a color to each element in a vector [message #76573] Tue, 14 June 2011 00:24
Gray is currently offline  Gray
Messages: 253
Registered: February 2010
Senior Member
On Jun 13, 10:55 am, "le.davide" <le.dav...@tiscali.it> wrote:
> On Jun 12, 4:42 pm, Gray <grayliketheco...@gmail.com> wrote:
>
>> On Jun 12, 9:25 am, "le.davide" <le.dav...@tiscali.it> wrote:
>
>>> Dear all,
>>> consider a scatter plot of the couple of points (x,y), where each x
>>> and y is an array. Do you know if it is possible to associate a color
>>> to each element according to its position in the vector?
>>> ...I don't know of much this is clear.
>>> Thanks in advance.
>
>> Or rather, colors=scale_vector(indgen(n_elements(x)),0,255)
>
> Thanks for the suggestion but I get the error message:
> PLOT: Expression must be a scalar or 1 element array in this context:
> COLORS.

That's because you're using PLOT and not PLOTS, which lets you specify
a vector of colors.
Re: Associate a color to each element in a vector [message #76581 is a reply to message #76573] Mon, 13 June 2011 10:55 Go to previous message
le.davide is currently offline  le.davide
Messages: 18
Registered: November 2010
Junior Member
On Jun 12, 4:42 pm, Gray <grayliketheco...@gmail.com> wrote:
> On Jun 12, 9:25 am, "le.davide" <le.dav...@tiscali.it> wrote:
>
>> Dear all,
>> consider a scatter plot of the couple of points (x,y), where each x
>> and y is an array. Do you know if it is possible to associate a color
>> to each element according to its position in the vector?
>> ...I don't know of much this is clear.
>> Thanks in advance.
>
> Or rather, colors=scale_vector(indgen(n_elements(x)),0,255)

Thanks for the suggestion but I get the error message:
PLOT: Expression must be a scalar or 1 element array in this context:
COLORS.
Re: Associate a color to each element in a vector [message #76583 is a reply to message #76581] Sun, 12 June 2011 14:50 Go to previous message
David Fanning is currently offline  David Fanning
Messages: 11724
Registered: August 2001
Senior Member
le.davide writes:

> consider a scatter plot of the couple of points (x,y), where each x
> and y is an array. Do you know if it is possible to associate a color
> to each element according to its position in the vector?

Here is an example of a scatterplot that uses colors like
this:

http://www.idlcoyote.com/tips/scatter3d.html

Cheers,

David


--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thue. ("Perhaps thos speakest truth.")
Re: Associate a color to each element in a vector [message #76584 is a reply to message #76583] Sun, 12 June 2011 13:42 Go to previous message
Gray is currently offline  Gray
Messages: 253
Registered: February 2010
Senior Member
On Jun 12, 9:25 am, "le.davide" <le.dav...@tiscali.it> wrote:
> Dear all,
> consider a scatter plot of the couple of points (x,y), where each x
> and y is an array. Do you know if it is possible to associate a color
> to each element according to its position in the vector?
> ...I don't know of much this is clear.
> Thanks in advance.

Or rather, colors=scale_vector(indgen(n_elements(x)),0,255)
Re: Associate a color to each element in a vector [message #76585 is a reply to message #76584] Sun, 12 June 2011 13:41 Go to previous message
Gray is currently offline  Gray
Messages: 253
Registered: February 2010
Senior Member
On Jun 12, 9:25 am, "le.davide" <le.dav...@tiscali.it> wrote:
> Dear all,
> consider a scatter plot of the couple of points (x,y), where each x
> and y is an array. Do you know if it is possible to associate a color
> to each element according to its position in the vector?
> ...I don't know of much this is clear.
> Thanks in advance.

So, what you probably want is something like this.

colors = indgen(n_elements(x))
plots, x, y, color=colors, psym=1
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