Adding a color bar legend similar to showResourceMapping

I'm trying to create a function similar to showResourceMapping (comm.OFDMDemodulator). The function create a resource map and adds a "color bar legend" to tell what the different color mean. An example is shown below:

I'm currently using pcolor() to create a similar map, but I cant figure out how to create this "color bar legend". Any clue on how can I create this type of legend ?

I'm might as well use any other image plotting function to visualize the map if needed.

Answer 1

[Michael]

I'll answer my own question.

I have used colormap(parula(4)); after ploting to have a discrete color map and I have set the color bar 'TicksLabels' property to the proper labels.