cline

Draw a colored line in 2D or 3D

Description

There are several files on the FEX which deal with the plotting of colored lines, but they all have some drawbacks. I wrote a little file, which extends the scope of the submission by Kun Liu (s. below, hoping to deliver a general purpose file, which should work for most purposes.

SYNTAX
======
h = cline(x, y [, z, cdata])

INPUT
=====
x: vector with x-values
y: vector with y-values
z (opt.): vector with z-values
cdata (opt.): vector with color-data

2 input arguments => cdata = y; z=0
3 input arguments => cdata = z
4 i.a. & z = [] => cdata = y; z=0

OUPUT
=====
h: Handle to line (i.e. patch-object !!!)

Examples
========
t = 2*pi:.1:8*pi;

cline(sqrt(t).*sin(t), sqrt(t).*cos(t));
cline(sqrt(t).*sin(t), sqrt(t).*cos(t), t);
cline(sqrt(t).*sin(t), sqrt(t).*cos(t), t, rand(size(t))); view(3)
cline(sqrt(t).*sin(t), sqrt(t).*cos(t), [], rand(size(t))); view(3)

OK, hope you find this file useful

Sebastian

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
Linear 2D Plot with Rainbow Color
This submission has inspired the following:
Perceptually improved colormaps

• MATLAB release: MATLAB 7.0.4 (R14SP2)
• Other requirements: none

[Matt Bennett]

 

[Xavi Alonso]

it doesn't work for me when cdata is a matrix

[Sean Torrez]

Beautiful file, thanks a bunch. Quite simple, works well.

[Matteo Niccoli]

This is really a great submission. I can think of vaery many ways of using it.

For starters, in conjunction with Colorspace transforamtions
( www.mathworks.com/matlabcentral/fileexchange/28790-colorspace-transformations ) I used it for an example in my Perceptually improved colormaps submission. I used cline this way:

% J=jet(256);
% LJ=colorspace('RGB->Lab',J);
% figure; cline([1:1:256],LJ(:,1),LJ(:,1),[1:1:256],J);
% title ('L* plot for jet colormap','Color','k','FontSize',12);

Also, as I was reading Steve's post on Lab based colormaps (thank you Steve!), I used cline this way to help me visualize things (notice again I used colorspace):

% radius = 50;
% theta = linspace(0, pi/2, 256).';
% a = radius * cos(theta);
% b = radius * sin(theta);
% L = linspace(0, 100, 256).';
% Lab = [L, a, b];
% RGBhlx=colorspace('RGB<-Lab',(Lab));
% figure; cline(a, b, L, L,RGBhlx); view(3);
% VIEW(-165,-15);

[Natasha]

Great, works perfectly, thanks

[Jaap]

Thanks for the post, I find it very useful. Do you perhaps know a way to increase the thickness of the line? Adding filled circular patch markers does do something, but the markersize makes a very sharp transition at 4.8-4.9.

[Sebastian Hölz]

@Jaap:

Use the following syntax:

fig = figure;
h = cline(...);
set(h,'linewidth',5)

The increased line-width will not be displayed, if you use "painters" as renderer for your figure. Therefore, you will have to change it:

set(fig, 'renderer', 'zbuffer')

- or -

set(fig, 'renderer', 'opengl')

Cheers

Sebastian