• option("collapse_unused_arg_action") regulates how generic functions (such as the Fast Statistical Functions) in the package react when an unknown argument is passed to a method. The default action is "warning" which issues a warning. Other options are "error", "message" or "none", whereby the latter enables silent swallowing of such arguments.

• option("collapse_mask") can be used to create additional functions in the collapse namespace when loading the package, which will mask some existing base R and dplyr functions. In particular, collapse provides a large number of functions that start with 'f' e.g. fsubset, ftransform, fdroplevels etc.. Specifying options(collapse_mask = c("fsubset", "ftransform", "fdroplevels")) before loading the package will make additional functions subset, transform, and droplevels available to the user, and mask the corresponding base R functions when the package is attached. In general, all functions starting with 'f' can be passed to the option. There are also a couple of keywords that you can specify to add groups of functions, and 2 special functions:

• "manip" adds data manipulation functions: fsubset, ftransform, ftransform<-, ftransformv, fcompute, fcomputev, fselect, fselect<-, fgroup_by, fgroup_vars, fungroup, fsummarise, fmutate, frename, findex_by, findex

• "helper" adds the functions: fdroplevels, finteraction, funique, fnunique, frange, fnlevels, fnrow and fncol.

• "fast-fun" adds the functions contained in the macro: .FAST_FUN.

• "fast-stat-fun" adds the functions contained in the macro: .FAST_STAT_FUN.

• "fast-trfm-fun" adds the functions contained in: setdiff(.FAST_FUN, .FAST_STAT_FUN).

• "all" turns on all of the above, and additionally exports a function n() for use in summarise and mutate, and masks base::table() by the much faster qtab() function.

• Since v1.8.8 it is also possible to pass "n" and "qtab" directly to the option.

Note that none of these options will impact internal collapse code, but they may change the way your programs run. "manip" is probably the safest option to start with. Specifying "fast-fun", "fast-stat-fun", "fast-trfm-fun" or "all" are ambitious as they replace basic R functions like sum and max, introducing collapse's na.rm = TRUE default and different behavior for matrices and data frames. These options also change some internal macros so that base R functions like sum or max called inside fsummarise, fmutate or collap will also receive vectorized execution. In other words, if you put options(collapse_mask = "all") before loading the package, and you have a collapse-compatible line of dplyr code like wlddev |> group_by(region, income) |> summarise(across(PCGDP:POP, sum)), this will now receive fully optimized execution. Note however that because of collapse's na.rm = TRUE default, the result will be different unless you add na.rm = FALSE.

In General, this option is for your convenience, if you want to write visually more appealing code or you want to translate existing dplyr codes to collapse. Use with care! Note that the option takes effect upon loading the package (code is in the .onLoad function), so it needs to be set before any function from the package is accessed in any way by any code you run. A safe way to enable it is by using a .Rprofile file in your user or project directory (see also here, the user-level file is located at file.path(Sys.getenv("HOME"), ".Rprofile") and can be edited using file.edit(Sys.getenv("HOME"), ".Rprofile")), or by using a .fastverse configuration file in the project directory.

• option("collapse_F_to_FALSE"), if set to TRUE, replaces the lead operator F in the package with a value FALSE when loading the package, which solves issues arising from the use of F as a shortcut for FALSE in R codes when collapse is attached. Note that F is just a value in the base package namespace, and it should NOT be used in production codes, precisely because users can overwrite it by assignment. An alternative solution to invoking this option would also just be assigning a value F <- FALSE in your global environment.