Color 2D plot according to external vector

I have a (10 x 501) matrix Y of, let's say, absorbances values from spectroscopic data. I have a (1 x 501) vector X of, let's say, corresponding wavenumbers. And I have a (1 x 10) vector Z of properties referring to the samples for which the Y values where recorded. I simply want to do plot(X,Y) and color the different lines according to the corresponding values of Z, i.e. a line corresponding to high Z value will have a different color from a line for which the Z value is small. But 2 samples with same Z values will have the same color for the 2 lines.

Basically I would like to reproduce what is available with scatter(X,Y,size,Z)....but for 2D plot and lines. Thanks for your help

Answer 1

[Daniel Shub]

Something like this might work:

Create some dummy data:

x = sort(randn(1, 501));
y = randn(10, 501)+repmat(5*(1:10)', 1, 501);
z = rand(10,1)*100;

Plot the data

colorMap = jet(length(unique(z)));
set(gcf, 'ColorMap', colorMap);
h = plot(x,y);

Change the color of the lines:

[~, ~, colorNo] = unique(z);
for icolor = 1:length(unique(z))
  set(h(colorNo == icolor), 'color', colorMap(mod(icolor-1, length(colorMap))+1, :))
end

set(gca, 'CLim', [min(z), max(z)])
colorbar

[Daniel Shub]

Edited to address comments

Answer 2

[Sebastien]

Hi, Thanks for your reply. However, at the end of the code, if I do colorbar, it goes from 1 to 64 range....while the z data in your example are between 1 and 4.... Basically, if I have 4 colors for the lines (which I have), I would expect to have only 4 colors in the colorbar (which I haven't).... Also your z data are integers, which are even replicated, while my data data would be values (e.g. percentages) with 2 decimals and with or without duplicated.... Thanks for your help.

[Daniel Shub]

You should really add this as a comment to my answer. See my edited answer.

Answer 3

[Sebastien]

If I can add....

x=[100:600];

y=rand(25,501);

z=rand(10,1)*100;

And I want to plot (x,y) with the lines having a color related to the z values (from red=high z values to blue = low z values for instance if we keep a jet colormap).

Thanks for your help.

[Daniel Shub]

You should add this to as a comment to my answer and not as an answer.

[Sebastien]

Many thanks for the edited code...

However in your code, the colorbar now displays 10 levels, which is fine....but which do not reflect at all the z values....

In the example, z values range from 0 to 100, while colorbar goes from 1 to 11....I would really like to have the colorbar reflecting the z values and the colors of the lines reflecting as well the intensity of the z values....Basically what scatter(X,Y,size,Z) does ....but for 2D plot and lines

[Daniel Shub]

I edited the code again ...