How to find the average of numbers within a specified range : I am using the 'diamonds' dataset from ggplot2 and am wanting to find the average of the 'carat' column. However, I want to find the average every 0.1:

**Between** 

0.2 and 0.29
        
0.3 and 0.39
        
0.4 and 0.49
        
etc.

