multiple colours in a trajectory plot

I have a time series X, which I can plot in x-y plane.

plot(X(:,1), X(:,2), 'r.')

This gives a red dot colour. What I want to do is I want to make this graph such that the colour represents the colour of the rainbow. (Red at the start, violet in the end) This is so we can give a time sense of the trajectory.

How do we do this?

Answer 1

[Star Strider]

Try this:

X = [(0:50)' sin((0:50)*pi/10)'];                               % Create ‘X’

cm = colormap(jet);                                             % Approximates Spectrum
X(end,2) = NaN;                                                 % Set Last Value To ‘NaN’ To Create Line
c = flipud(X(:,1));                                                     % Define Colours To Scale With ‘X(:,1)’

figure
patch(X(:,1), X(:,2), c, 'EdgeColor','interp')

EDIT — Added plot image.

[CLARK KENDRICK GO]

Thanks for this. Now, I want to ask if there is a way to change from 'line' to 'dots'.

As in likes of plot(X(:,1),X(:,2),'r.') <-- red dots

[Walter Roberson]

You can

pointsize = 15;
scatter(X(:,1), X(:,2), pointsize, (1:size(X,1)).', '.');
colormap(jet)

[Star Strider]

@Walter — Thanks

[Niklas Kurz]

Again just coming in clutch!

[Niklas Kurz]

Would also be worth knowing how to apply the color map upside down, with other words going up the y-axis

[Walter Roberson]

%flip the current colormap
colormap(flipud(colormap))

or for fixed colormap

colormap(flipud(jet))

Answer 2

[Walter Roberson]

It is not possible to have multiple colors on a line create by a single call to plot() or the underlying function line() .

You can look in the File Exchange for a couple of contributions for drawing colored lines. One of them uses surface objects, and one of them uses patch objects.