Contour bar level step

I have 5 different group of data which have different properties. I want to show them in the contour plot by just five colors. But it shows me some extra colors both in the plot and in the color bar. How can I be specific about the colors? Thanks.

[Walter Roberson]

When you call contour() are you passing in the number of contours you want, or are you passing in a vector of contour levels?

[Nahid Taheri]

No, how should I do that?

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/contour.html

contour(Z,v) draws a contour plot of matrix Z with contour lines at the data values specified in the monotonically increasing vector v.