What is sql equivalent of i in a typical data table query?
Answers
This vignette introduces the data.table syntax, its general form, how to subset rows, select and compute on columns, and perform aggregations by group. Familiarity with data.frame data structure from base R is useful, but not essential to follow this vignette.
Data analysis using data.table
Data manipulation operations such as subset, group, update, join etc., are all inherently related. Keeping these related operations together allows for:
concise and consistent syntax irrespective of the set of operations you would like to perform to achieve your end goal.
performing analysis fluidly without the cognitive burden of having to map each operation to a particular function from a potentially huge set of functions available before performing the analysis.
automatically optimising operations internally, and very effectively, by knowing precisely the data required for each operation, leading to very fast and memory efficient code.
Briefly, if you are interested in reducing programming and compute time tremendously, then this package is for you. The philosophy that data.table adheres to makes this possible. Our goal is to illustrate it through this series of vignettes.
SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.