Calculating subtotals in R

Question

I have a data frame with 900,000 rows and 11 columns in R. The column names and types are as follows:

column name: date / mcode / mname / ycode / yname / yissue          


        

Answer 1

There is a R package called sqldf that enables you to use SQL commands on R data.frames. Besides like you already said, GROUP BY would be nice. You can easily store your data in a local MySQL database and connect to R using the package RMySQL (You can use most other DBMS too but MySQL is the easiest to set up).

As far as I can judge it plyr is a great package, too. But from the way you ask and compare your problem to GROUP BY, I guess you know something about SQL, so using this might be easier for you. There are comfortable functions like dbReadTable, plus if your data grows bigger you can select only subparts of your data to only run your analysis with what you really need.