How to add fixed Colorbar based on a vector for 2D scatter plot with 3 vectors

I want to compare two [2D scatter] plots that both have three variables (x,y,z). I'm plotting x against y and showing vector z for both plots by color. I need to make the colorbar fixed so I can compare the two plots. How can I make this colorbar range fixed for both? Thank you in advance

if true
figure 
pointsize = 10;
scatter(x1, y1, pointsize, z1)
colorbar;
figure 
pointsize = 10;
scatter(x2, y2, pointsize, z2)
colorbar;
end

[Jon Hinwood]

I have tried using caxis, which I use with the plot command, but it has no effect and the range is set automatically to the full range of my data. I have tried placing the caxis command before, after the specification of colormap and before and after the call to scatter and in all 4 positions. Also tried rebooting computer and repeating the trials.

I did find that caxis only worked with plot if the caxis command was after the colormap and before the plot command. I an using Matlab R2019b Academic with Windows 10 both fully updated. Help please!

Jon. 15 Oct 2020

Answer 1

[Star Strider]

One option is to normalize the ‘z’ values by scaling them with respect to the range of both ‘z1’ and ‘z2’:

figure 
pointsize = 10;
scatter(x1, y1, pointsize, (z1-min([z1(:);z2(:)]))/max([z1(:);z2(:)]))
colorbar;
figure 
pointsize = 10;
scatter(x2, y2, pointsize, (z2-min([z1(:);z2(:)]))/max([z1(:);z2(:)]))
colorbar;

The colorbar will be the same for both.

[Yaser Khojah]

Thanks for your help. I tried it and I still do not see them matching. For example colorbar for 0.5 in figure 1 is not the same in as figure 2. Is there anyway I can keep the original values. My z values are between [2000 and 7000]. Thanks

[Star Strider]

It will likely be worthwhile to experiment with the caxis (link) function:

figure 
pointsize = 10;
scatter(x1, y1, pointsize, z1)
colormap(jet(25))
caxis([0 max([z1(:);z2(:)])])
colorbar;
figure 
pointsize = 10;
z2c = (z2-min([z1(:);z2(:)]))/max([z1(:);z2(:)]);
scatter(x2, y2, pointsize, z2)
colormap(jet(25))
caxis([0 max([z1(:);z2(:)])])
colorbar;

[Yaser Khojah]

Thanks a lot for your help. It worked finally. I just need to find a better way know to see these colors since I have problem with seeing color haha but thanks a lot.

[Star Strider]

As always, my pleasure.