[R-Forge #5248] implement "set" (as in setdiff, union etc..) operations for data.tables for convenience

[arunsrinivasan]

Submitted by: Arun ; Assigned to: Nobody; R-Forge link

data.table has already a very efficient way for getting unique and duplicated. It takes 0.5 seconds where base's unique takes 8 seconds for example - check this benchmark on rpub.

Similarly, why not use the internal engine to generate set operations on data.table?

• setdiff
• union
• intersect
• setequal

Condition: Number of columns and column classes should match.

[jangorecki]

setdiff function name might be replaced except (postgres, sqlserver naming convention), to not interfere with set* used by by reference functions.

[jangorecki]

Nice reference regarding that feature: http://www.postgresql.org/docs/9.5/static/queries-union.html
Set ops * ALL basic examples: http://gplivna.blogspot.co.uk/2008/01/minus-all-and-intersect-all-in-oracle.html
Set ops * ALL design description: https://db.apache.org/derby/papers/Intersect-design.html