Variable Subsetting & Heat Map

#1
Hey all,

Being a novice programming in R I am wondering if anyone could assist me. I have two variables in a data set; date and a numeric variable.

Date Number
6/06/2013 10
.... ....
.... ....

I am wanting to create a heat map with half year intervals (2013H1, 2013H2...) and numeric intervals (<10, 11-20, 21-30...).

Would anyone be able to assist?