Frequency count of two column in R

Question

I have two columns in data frame

2010  1
2010  1
2010  2
2010  2
2010  3
2011  1
2011  2

I want to count frequency of both columns and get

Answer 1

library(data.table)

oldformat <- data.table(oldformat)  ## your orignal data frame
newformat <- oldformat[,list(Freq=length(m)), by=list(y,m)]