Colormap for multline plot

How do I change the colormap of a multiline plot and have it change the colors of the existing lines? I am using Matlab 2018b. Here is a simple example.

x = rand(10,1000);
t = 0:999;
plot(t, x)
colormap winter
colormap white
colormap flag
fh = gcf;
fh.Colormap = colormap('flag');
fh.Children(1).Colormap = colormap('flag');

For me, the colors of the lines do not change. The following also did not work, the lines are plotted using the "default" color scheme.

fh2 = figure;
fh2.Colormap = colormap('flag');
ax = axes(fh);
ax = axes(fh2);
ax.Colormap = colormap('flag');
plot(ax, t, x)

Invoking "colorbar" shows a colorbar using the desired colormap. Using colormap with surf(peaks) does change the color of that plot. How do I change the colormap of a 2D multiline plot?

Answer 1

[Bhaskar R]

"A colormap is matrix of values between 0 and 1 that define the colors for graphics objects such as surface, image, and patch objects. MATLAB® draws the objects by mapping data values to colors in the colormap." from https://in.mathworks.com/help/matlab/ref/colormap.html

But you are trying to apply colormap to line data instead of surface, image, patch data objects.

You can apply 'color' field to line data. This answer can help you https://in.mathworks.com/matlabcentral/answers/396900-how-can-i-change-the-line-color-in-a-2d-graph-using-colormap#comment_560420

Answer 2

[Sindar]

I believe this should work:

mylines = plot(t, x);
set(mylines,{'Color'},flag(length(mylines)))

For 2019b+, colororder is the function that controls this. I think the way you'd pass a colormap is

colororder(flag)

but you might need

colororder(flag(100))

[Sindar]

BTW, lines is the default

[Matt]

This does not work

Error using matlab.graphics.char.primitive.Line/set

Answer 3

[Walter Roberson]

line() colors are not affected by the colormap, ever. They are affected by the axes ColorOrder property.

In the release you are using, changing the ColorOrder property never affects lines that have already been drawn: you have to set the Color property of each of the line() objects that already exists.

Starting in r2019b, there is a new colororder() function that can set the axes ColorOrder property. As well, by default changing the ColorOrder will affect lines that have already been drawn. (I do not recall at the moment how to turn that off)

[Matt]

Looks like another reason to roll to the newer release. After reading the documentation tagged to the functions you mention I saw this wonderful statement "Changing the order has no effect on existing plots. However, many graphics functions reset the color order back to the default value before plotting."