How do I create a color bar to correspond to my jet color scheme?

I've used the jet function to create a gradient of color, such that every color is a different voltage. How do I make a color bar given the RGB array I made with the jet function and assign the max and min voltage values on the color bar for my figure? Thanks!

Answer 1

[Chad Greene]

Try this:

Plot some data:

surf(peaks)

Change the colormap*:

colormap(jet) 

Add a colorbar and put a label on it:

cb = colorbar; 
ylabel(cb,'voltage') 

Set colorbar limits:

caxis([-8 4]) 

That'll create this figure:

* But note, there are some perceptual issues with using jet to represent numbers. For those reason's the jet colormap has fallen out of fashion in recent years. Read up on #endrainbow if you're curious to know more.

[Alexandria Will-Cole]

I am looping through data and each new data set is assigned a color based on the voltage value that the measurement is taken at. It's not a surface plot... It's an xy scatter plotted with a color and then I use 'hold on' then continue with next data set.

I tried the commands you gave, but it did not add a color bar. Is there a different way I should implement it for the situation I described?

[Chad Greene]

It should work just as well for scatter plots as it does for the surface plot. Try this:

x = rand(100,1); 
y = rand(100,1); 
z = rand(100,1); 
scatter(x,y,50,z,'filled')
cb = colorbar; 
ylabel(cb,'voltage'); 
caxis([0.2 0.8])

[Steven Lord]

Please create a small synthetic dataset (say ten to twenty points) that is similar to your actual data and show the code you use to create your scatter plot using that synthetic dataset. After that describe specifically how the figure created by that code differs in appearance from the code you want. Perhaps with a concrete example we can run and use to experiment we can offer a suggestion on how to achieve or approach your goal.

[Alexandria Will-Cole]

This worked finally! Thank you!

Answer 2

[Image Analyst]

Use the caxis() function.

[Alexandria Will-Cole]

This did not work. Thanks though.