Register a reduction operation. — register

Stores a user-defined reduction function under the given name so that it can be retrieved by get_reduction() and invoked during query evaluation.

Usage

register_reduction(name, fn, overwrite = FALSE, source = NULL)

Arguments

name: Op name (character scalar, matches token in query strings).
fn: Function function(x, ...) where x is a numeric vector or matrix column and ... collects named parameters.
overwrite: Logical scalar; set to TRUE to replace an already- registered operation.
source: Optional "file:line" string identifying where the registration happened. Used in the conflict error message; auto-captured from the caller's srcref if omitted.

Value

Invisibly NULL.

Examples

register_reduction("Median_example", function(x, ...) median(x, ...), overwrite = TRUE)
registered_reductions()
#>  [1] "Count"          "GeoMean"        "Max"            "Mean"          
#>  [5] "Median"         "Median_example" "Min"            "Mode"          
#>  [9] "Quantile"       "Std"            "StdN"           "Sum"           
#> [13] "Var"            "VarN"