I am using matplotlib

In plot() or bar(), we can easily put legend, if we add labels to them. but what if it is a contourf() or imshow()

I know there is a colorbar() which can present the color range, but it is not satisfied. I want such a legend which have names(labels).

For what I can think of is that, add labels to each element in the matrix, then ,try legend(), to see if it works, but how to add label to the element, like a value??

in my case, the raw data is like:

1,2,3,3,4
2,3,4,4,5
1,1,1,2,2

for example, 1 represents 'grass', 2 represents 'sand', 3 represents 'hill'... and so on. imshow() works perfectly with my case, but without the legend.

my question is:

1. Is there a function that can automatically add legend, for example, in my case, I just have to do like this: someFunction('grass','sand',...)

2. If there isn't, how do I add labels to each value in the matrix. For example, label all the 1 in the matrix 'grass', labell all the 2 in the matrix 'sand'...and so on.

Thank you!