Build data.table implementation of lookup_by_column. We do this here as rqdatatable is a data.table aware package (and rquery is not).

make_dt_lookup_by_column(pick, result)

Arguments

pick

character scalar, name of column to control value choices.

result

character scalar, name of column to place values in.

Value

f_dt() function.

Examples

df = data.frame(x = c(1, 2, 3, 4), y = c(5, 6, 7, 8), choice = c("x", "y", "x", "z"), stringsAsFactors = FALSE) make_dt_lookup_by_column("choice", "derived")(df)
#> x y choice derived #> 1: 1 5 x 1 #> 2: 2 6 y 6 #> 3: 3 7 x 3 #> 4: 4 8 z NA
# # base-R implementation # df %.>% lookup_by_column(., "choice", "derived") # # # data.table implementation (requies rquery 1.1.0, or newer) # # df %.>% lookup_by_column(., "choice", "derived", # # f_dt_factory = rqdatatable::make_dt_lookup_by_column)