R is my mistress and my wife. Hadley Wickham held the ceremony. Data.Table is the glue that holds together our tenuous marriage. cats[color="brown",summary(t

R is my mistress and my wife. Hadley Wickham held the ceremony. Data.Table is the glue that holds together our tenuous marriage. cats[color="brown",summary(tooth_length),by=list(breed,age)]. This line of code will efficiently grab all the brown cats in your data and summarize their tooth length by mean, median and other quartiles then break it out by the cats breed and age. Every time I use a language I can't lapply I despise the language and all those involved. R is hugely inconsistent and terribly inefficient. But its also the most irresistible blend of lispy and object oriented for when you actually need to get data analysis done.