Using data.table package inside my own package

by

Andrie’s guess is right, +1. There is a FAQ on it (see vignette("datatable-faq")), as well as a new vignette on importing data.table:

FAQ 6.9: I have created a package that depends on data.table. How do I
ensure my package is data.table-aware so that inheritance from
data.frame works?

Either i) include data.table in the Depends: field of your DESCRIPTION file, or ii) include data.table in the Imports: field of your DESCRIPTION file AND import(data.table) in your NAMESPACE file.

Further background … at the top of [.data.table (and other data.table functions), you’ll see a switch depending on the result of a call to cedta(). This stands for Calling Environment Data Table Aware. Typing data.table:::cedta reveals how it’s done. It relies on the calling package having a namespace, and, that namespace Import’ing or Depend’ing on data.table. This is how data.table can be passed to non-data.table-aware packages (such as functions in base) and those packages can use absolutely standard [.data.frame syntax on the data.table, blissfully unaware that the data.frame is() a data.table, too.

This is also why data.table inheritance didn’t used to be compatible with namespaceless packages, and why upon user request we had to ask authors of such packages to add a namespace to their package to be compatible. Happily, now that R adds a default namespace for packages missing one (from v2.14.0), that problem has gone away :

CHANGES IN R VERSION 2.14.0
* All packages must have a namespace, and one is created on installation if not supplied in the sources.

More Related Contents:

  1. Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
  2. Extract row corresponding to minimum value of a variable by group
  3. Group by multiple columns and sum other multiple columns
  4. Left join using data.table
  5. Summarizing multiple columns with data.table
  6. Why is rbindlist “better” than rbind?
  7. Apply multiple functions to multiple columns in data.table
  8. data.table join then add columns to existing data.frame without re-copy
  9. Convert column classes in data.table
  10. Using lists inside data.table columns
  11. Perform a semi-join with data.table
  12. Find the intersection of overlapping ranges in two tables using data.table function foverlaps
  13. Adding new columns to a data.table by-reference within a function not always working
  14. Referring to data.table columns by names saved in variables
  15. Calculate multiple aggregations on several variables using lapply(.SD, …)
  16. Merge rows in a dataframe where the rows are disjoint and contain NAs
  17. Efficient row-wise operations on a data.table
  18. Replace logical values (TRUE / FALSE) with numeric (1 / 0)
  19. from data table, randomly select one row per group
  20. How to change type of target column when doing := by group in a data.table in R?
  21. Insert a row in a data.table
  22. rolling joins data.table in R
  23. Efficiently merging two data frames on a non-trivial criteria
  24. Using data.table i and j arguments in functions
  25. R data.table breaks in exported functions
  26. Applying a function to each row of a data.table
  27. Empty factors in “by” data.table
  28. How to use data.table within functions and loops?
  29. What you can do with a data.frame that you can’t with a data.table?
  30. data.table: anonymous function in j

Leave a Comment