Use [.data.table (currently [ is dispatched to the data.frame() method)

[MichaelChirico]

See https://cran.r-project.org/web/packages/data.table/vignettes/datatable-importing.html, relevant section "data.table in Imports but nothing imported"

Basically, because fastDummies Imports data.table but does not importFrom(data.table, ...) in its NAMESPACE, to be conservative data.table assumes that fastDummies is "unaware" of data.table [ semantics and dispatches to [.data.frame.

That's evident e.g. here:

fastDummies/R/dummy_cols.R

Line 223 in 1ff6181

.data <- .data[-which(names(.data) %in% char_cols)]

Where that code won't work under [.data.table. The data.table equivalent is:

.data[, !..char_cols]
# or
.data[, !char_cols, with = FALSE]
# or
.data[, .SD, .SDcols = !char_cols]

The solution is

1. Set .datatable.aware = TRUE anywhere in the package namespace
2. Edit [ usages to use [.data.table semantics where appropriate.

Happy to file a PR fixing this.

If [.data.frame usage is intentional, I'd recommend (1) using as.data.frame() or data.table::setDF() to make the use of [.data.frame more intentional/explicit or (2) defining .datatable.aware=FALSE in your namespace to make it clearer that this is intentional.

[jacobkap]

Hi, please make a PR. Thanks!